Step-by-step installation:

1. Download the latest relase from releases.
2. Extract the contents of the archive next to the game executable file in your games folder. (e.g. for Unreal Engine games, it's <path-to-game>\Game-or-Project-name\Binaries\Win64 or WinGDK\)`^1`
3. Rename OptiScaler.dll to nvngx.dll (For older builds, file name is already nvngx.dll, so skip this step)
4. Run EnableSignatureOverride.reg from DlssOverrides folder and confirm merge.$^2$`^3`

[1] This package contains latest version of libxess.dll and if the game folder contains any older version of the same library, it will be overwritten. Consider backing up or renaming existing files.

[2] Normally Streamline and games check if nvngx.dll is signed, by merging this .reg file we are overriding this signature check.

[3] Adding signature override on Linux - There are many possible setups, this one will focus on Steam games:

• Make sure you have protontricks installed
• Run in a terminal protontricks regedit, replace with an id for your game
• Press "registry" in the top left of the new window -> Import Registry File -> navigate to and select EnableSignatureOverride.reg
• You should see a message saying that you successfully added the entries to the registry

If your game is not on Steam, it all boils down to opening regedit inside your game's prefix and importing the file.