It's probably because you need the tracks they are using, look in the server list at what track is being used, google it, once you find it, download it and install it, then you should be able to join the server. Then when the track changes, you will probably get booted again, once again, look in the server list at what track is being used, google it, once you find it, downlaod and install it. Keep repeating those steps until you have every track on the server, then you should not get booted anymore.
If your lucky, you could find a website related to the server and get a list of tracks then install them all in one go.
If you do have all the tracks already, then make sure you have the correct version of the mod.