Modder woodboy90 has released version 1.2 of the Quake 3 Arena RTX Remix Mod Demo. The new build is posted on ModDB as a standalone download (3.33 GB), which should make installation simpler compared to earlier versions.
Highlights of the update:
Improved normal and height map textures
Improved lighting
New particle effects for Quad Damage and Lightning Gun
Remastered maps: q3dm3, q3dm17, q3tourney1
Remastered player models: Slash, Keel (Blue), Bones, Sorlag, Mynx
Mouse input switched to DirectInput
Easier mod installation
The ModDB notes also mention that older versions (1.0 / 1.0.1) are no longer supported and aren’t required to install.