Once the addon is installed, you can find the AQUA tab on the side panel of the 3D view window. With the AQUA tab selected, click the Get Started button to set up your scene for using the addon. The panel it creates will be divided into two sections:

RIVERS

Draw River/Stop Drawing - toggle on and off the river drawing curve tool. 

Width - set the river's width

Depth - set the river's depth

Noise Scale  - scale the water noise pattern

Enable Custom Rocks - toggle between using procedurally generated rocks, and custom rock models. For custom rock models to be used they must be placed within the AQUA_interior_rocks collection(for rocks within the river) or the AQUA_contour_rocks(for rocks along the water edge) collection in the outliner. 

Density - density of rocks(custom or generated)

Min distance - minimum distance between rocks. 

Seed - random seed value for scattering. 

Min Size - minimum rocks size for random scaling.

Max Size - maximum rock size for random scaling.

Water Colour - set material colour for the water.

Water Density - set water volume density.

Foam Size - colour ramp to control foam size.

Foam Strength - set foam strength.

Rock Colours - colour controls for procedural rocks.

OCEANS

To have proper interaction with the foam, place your shoreline model within the AQUA_Shore collection, and any other objects sitting in the water into the AQUA_objects collection in the outliner. 

Draw Ocean/Stop Drawing - toggle on and off the ocean drawing curve tool.

Length - control for how far out to sea the ocean stretches.

Depth - control for ocean depth. 

Wave Strength - control wave strength.

Noise Strength - control water noise strength.

Subdivision - control subdivision levels.

Water Colour - control water material colour. 

Water Density - control water volume density.

Shoreline Foam Control/Proximity Foam Control - Controls for the shoreline and proximity foam visibility and strength. By default there will be no foam. With objects in the AQUA_shoreline and AQUA_object collections in the outliner, bring the black and white handles of the colour ramps closer to the center of the colour ramp, and adjust from there to your liking. If the two collections are empty of objects, keep the colour ramps as they are by default, or the foam will not be placed properly. 

Whitecaps - strength of foam whitecaps on noise peaks. 

Water Detail Strength - series of controls for the water shader detail noise patterns. 

TROUBLESHOOTING

-Blender's curve drawing tools tend to have issues if the viewport clip start distance is below the default value. It is recommended to keep this value at the default  0.01

- There can be some strange intersections if the curves drawn become too extreme. Use the curve handles in edit mode to adjust the curve manually after drawing.