To use this product, append the node tree wood_facade from the file you downloaded from blendermarket into your own project. This should add a plank_profile object into your scene, which you can later use to adjust the shape of the wood planks. To clad your building in it's new wood facade, give it a Geometry Nodes modifier that uses the appended node tree. At this point, nothing should have happened. Planks will show up once you give some of your object's faces the wood_facade material, which should also have been added to the file. If this doesn't work, make sure you are using version 4.1 or newer. You may want to add a Normals>Smooth by Angle modifier to sharpen some of the edges.

The Plank Profile object should be a mesh containing a closed loop of edges in the X-Z-plane filled by a face. Feel free to move, dissolve or add points to adjust the shape of the planks. It functions like the bevel object on a curve.

array height determines how far each plank is offset from the next. This should be adjusted with changes to the planks profile as it doesn't automatically accommodate a wider or narrower plank.

offset from facade functions similarly to the "Offset" option in the solidify modifier. It will shift the planks backwards and forewards in relation to the plane of the initial geometry.

scale factor can be used to change the scale of the siding. If a driver containing only the average scale of the current object in it's expression is added to this field, it will ensure true absolute size of the planks.

fine fitting cuts will enable or disable the boolean operation cutting into indiviual planks to match the facade's shape exactly.

remove facade will remove and entirely replace the initial faces with the planks if turned on. If the planks are set inwards with offset from facade = -1 to be flush with the front of the geometry, this value must be set True to reveal the planks.

make miter cut determines whether or not the planks meeting at a corner of the building are joined at an angle using a miter joint.

flip miter cut may need to be adjusted to make the miter cuts be in the correct orientation.

make vertical will turn the planks to run vertically down the facade instead of horizontally along it. This makes the miter cut options obsolete.

material seed is a seed for the random attributes contributing to the facades texture coordinates. Depending on the material, this will randomize it's appearence.

...which brings us to the materials:

By default, the node tree will bring a procedural charcoal-coloured wood material with it. An image texture-based material is also included in the product file (kudos to polyhaven.com for the textures). You are free to make your own materials for your facade. To make it work with the generated geometry, you need to use the provided custom texture coordinate attributes:

For procedural shading the attribute tex_coords_procedural provides texture coordinates for each plank centered on zero with the length of the plank oriented along Y. This can be used to create growth rings per plank using a wave texture set to Rings and Y. The attribute tex_coords_rnd provides a random offset per plank. Add this with a small factor to the texture coordinates to make the planks be cut "off center" from the tree's rings.

For image texture-based shading the attribute tex_coords_uv provides an unwrapping of each plank all in the same spot in UV space. This can also be useful in a procedural material to map screws or nails onto the planks. Use the addition of the attribute tex_coords_uv_offset at some appropriate factor to spread the planks out vertically in UV space each by a set increment. Use the addition of the attribute tex_coords_rnd_lengthwise at some appropriate factor to spread the planks out horizontally in UV space each by a random amount.

Check out the provided example materials for further insight.