The models at MaxRealms were originally designed for use in 3ds Max. Most do not have textures as image maps, but use the 3ds Max color swatches.
Any model on the site can, of course, be used in FPSC, but you will need to do some work on them as far as textures. As I use my models for FPSC, I will upload them as ready-to-use entities. If you use one of my models and get them game ready and post here, please keep in mind that you will need to include a license file such as the one included with the Street Light model I submitted here.
Lastly, I didn't create all the models on Max-Realms, so you need to contact the model's author for permission if you want to use his/her model in your game and distribute on this forum.
Cheers!
~Dave
http://www.max-realms.com