Drag and drop the "extension" folder into your root assettocorsa folder.
It is usually C:\Program Files (x86)\Steam\steamapps\common\assettocorsa

The filter looks great with the default "Pure" PPFilter and does not need custom Pure Settings.

I highly recommend trying out "C13 AEGIS", "C13 Camera Obscura" or "Pure Candy" PPFilters
with my Reshade as I feel they look more realistic together.

If you use any of these, use my custom Pure Configs to balance out the lighting and reflections,
especially if you have rain.

For the C13 PPfilters I've included a Brighter option as the default ones may be too dark at night.