Something like Git LFS will help with larger files like assets. Generally you would want to get into version control where you can merge assets and changes. Working on the same level will be difficult but as suggested on the forums previously one method is to separate the level into different layers, these could be different areas of the map. This still however will cause issues as you will need to manually import the other layer and copy and missing or new assets from the other user into a main level file.
Regarding transferring files to another user, this is between you and the other user - there should be no issues if the setup is correct and the same as yours as far as assets go.
Technical Community Manager
Here to help the community and social channels grow and thrive.
My personal belongings;
| My GitHub
| Splash Plugin