Install Mod:

Put the files of "Mod Files" folder in the main folder of the game.

Install Models:

Open OpenIV, and go to the file "update.rpf" in the "update" folder, 
go to update.rpf > x64 > levels > gta5 > generic > cutsobjects.rpf and add/replace the file "p_spinning_anus_s.ydr" and the file "p_med_jet_01_s.ydr" which is in "UFOs Models" folder.

If "cutsobjects.rpf" dont exist in the file "update.rpf", open OpenIV and go to file x64d.rpf > levels > gta5 > generic and extract the file "cutsobjects.rpf" and add it to update.rpf > x64 > levels > gta5 > generic.