How to install

Once you downloaded the add-on file, do not decompress the zip file.

Click Edit->Preferences->Add-ons->Install...

With the "Blender File View" window that opened, locate the zip file, select it and click "Install Add-on".

The add-on should then appear in the list, enable it by clicking on the checkbox:

When returning to Blender's main interface, in Edit mode you should now see a "Detailer" tab on the right side of any 3D view in Edit mode:

It is recommended to restart Blender after the add-on has been installed for the first time.

This should hopefully be it. If however you don't see that a "Detailer" has been added, try defining a file path for scripts in Edit->Preferences->File Paths-> Scripts. Then do the install process again. If this does still not work, don't hesitate to get in touch with me.

Parameters purposes

Most parameters do display a description when hovering on them with the cursor, but some are less easy to understand than others. A more in-depth explanation can be found here. 

Hull

Material: Material to apply on the hull style. All the materials present in your scene are available to choose from. This field need to have a material selected for the add-on to run properly. The vertices of the hull style will also receive an additional UV map named "mono_UVs". In this map, all faces of each plate will be given the same random UV coordinate, between 0 and 1. This is to help you differentiate hull plates in your material if you wish to.

Rivet: Generates rivets at the junction of different plates.

Plate detail probability: Probability of adding a detail on a hull quad face that is not already not used for a plate junction.

Plate separation depth: Depth of the crease between two plates.

Plate separation thickness: Thickness of the crease between two plates.

For the next set of parameters (Jittering, X/Y/Z axis points count, and Regular) it is important to understand how Voronoi cells work. Initially "feature points" are generated, a feature point is simply a position in 3D space. We then define the boundaries of Voronoi cells as the points in space at the same distance from 2 or more feature points.

The following parameters are only means to drive the distribution of the feature points.

The points are initially distributed on a 3 dimensional grid, and then a random offset can be added.

Jittering: Jittering distance for the Voronoi feature points. This is the random offset that is added to the grid distribution of feature points that will be used to separate hull plates. It gives a more chaotic/organic look to the boundary shape of the plates.

X/Y/Z axis points count: Number of slices for the feature points grid on the X/Y/Z axis. Try setting a value of 1 for two of the axis, and more for the last axis, your volume will be divided only along this axis.

Regular: If the slices are regularly spaced, or randomly spaced for this axis.

Random seed: Seed driving the random generation (set -1 to use a different seed each time). For the hull style, this influences the spacing of non regularly spaced slices (for Voronoi feature points), the jittering and the spawning of plate details.

High frequency

Material: Material to apply of the high frequency style. All the materials present in your scene are available to choose from. This field need to have a material selected for the add-on to run properly. The vertices of the high frequency style will also receive an additional UV map named "mono_UVs". In this map, each subdivision will be given a random UV coordinate, between 0 and 1. This is to help you differentiate details in your material if you wish to.

First inset depth: Depth of the inset applied first to all faces.

First inset thickness: Thickness of the inset applied first to all faces.

Details depth multiplier: Multiplier for the depth of the recursive insets.

Iterations: How many recursive geometry generation are performed. This is a very important parameter for the high frequency style. A higher value for this will lead to more details, but will also require exponential computing time.

Iterations before diverging: Level at which the recursive algorithm will stop using the same random seed. Set to -1 to always use the same seed, 0 to never use the same seed. This will help you giving a common structure to the first recursions. Allows to not just be completely random but have an infinity of sub-styles: try setting this parameter to 1, 2 or 3 and then browse through the random seeds.

Identical children probability: The probability that a subdivision spawns identical children, using the same random seed for the next generations.

Minimum depth identical: Minimum depth during which children stay identical before diverging. This is useful to get a sense of repetition and "man-made" while still retaining diversity for the smaller details.

Maximum depth identical: Maximum depth during which children stay identical before diverging.

Random seed: Seed driving the random generation (set -1 to use a different seed each time). For the high frequency style this influences every step of the geometry generation.

Structure

Material: Material to apply on the structure style. All the materials present in your scene are available to choose from. This field need to have a material selected for the add-on to run properly.

Rivets: Generate rivets on the structure's beams.

Depth: The depth of the holes between the beams.

Roudning edges: The number of edges used to round the angle formed by the beams.

Hole rounding: The size of the rounding.

Hole end width: Determines if the beams are straight or converge to meet each other.

Crease: If non 0, separates the structure style from the rest with a crease. This parameter drives the size of the crease.

Random seed: Doesn't influence anything yet for the structure style.