Hey there Elixnova.
I am a bit confused to what you need the project server file for. If you just want to import an image to use as a sprite, or a 3D object to use as a model, you should just be able to import the files through the engine itself.
I've made a video that covers this in the past, you can have a watch and follow along to see if it helps at all [ start at 2:00 ]:
If the above steps don't work for you, please let me know and I'll try to help you out further. Good luck!