Up to 9 client machines using FileMaker Pro can connect to a Database hosted by FileMaker Pro. The hosting does not need to be done with a copy of FileMaker Pro Advanced--it's features are intended to help you design databases--a regular copy of Filemaker will do. (It's safer not to make design changes to the database while it is being shared with others.)
Make sure the other users use Open Remote to find and connect to the database. Using a shared directory to access the file can damage it.