these models contain ripped content from other games and are against ToS of the forums. I would recommend you remove the link and ask this as a general question.
Now to answer your actual question: If you have a set of loose files that are in the p and tex format (they will appear as no file type in windows) you place them in a folder with the correct name "battle , World_us , Magic , etc" then place them all inside a folder.
Then in 7th heaven go to workshop -> pack/unpack IRO -> pack IRO from source folder. select the folder and pack it. then go to library -> import -> import from IRO library and select the new IRO you created. Refresh your library tab and place the new IRO in the correct spot on the load order. For a mod file group that contains multiple areas like battle, world, char etc i would make a differnt IRO for every category to allow for more customization.
once you have the IRO set like that go into your ff7 root folder and open your ff7open_gl.cfg and near the bottom you will find direct mode = off. change that off to say on. (if using 1.56 7h you can toggle direct on in the openGL settings)
Remove any other IRO that edits the same models and launch and enjoy.
