Download TAL Noisemaker from https://tal-software.com/products/tal-noisemaker and the move TALNoiseMaker-64.dll into the C:\Program Files\REAPER (x64)\Plugins directory. Restart Reaper, which will cause Reaper to load the DLL file. If this fails to work as expected, you can Options > Preferences.> VST > Re-scan or Clear cache/re-scan.
IMPORTANT - Do not provide C;\ as the base search directory, as this will search the entire PC for .dll files, which caused big problems for me (I had to uninstall and then reinstall Reaper).
Select FX and TAL Noisemaker should be one of the VST plugins.
You should now be able to use TAL Noisemaker in Reaper.