welcome to the forums.
This game/mod really uses either DX9 or DX10
This can be selected on the provided launcher.
Further a 32bit or 64bit client can be run (yes the game is this
Could You try if switching DX to 9 or 10 changes anything?
The DX12 shipped with W10 maybe breaks some legacy
support, and we well might be one?
There are more knowledgeable players to address You shortly, and they most certainly will ask You the same?
IPA_avatar beat me to the clock