Even with a genuine "full download," you may encounter problems.
In-game, open the ReShade menu (Home key) and ensure the "DisplayDepth" shader looks correct. This is critical for the RTGI effect to "see" the 3D world properly. Activate RTGI: reshade rtgi 033 download full
If you absolutely cannot pay the Patreon fee, Pascal Gilcher has released an older version (0.29.15) for free on GitHub (via the "ReShade Effects" repository). However, be aware: Even with a genuine "full download," you may