As someone who runs various mods for the servers, for every 1 person I see that properly joins, 2 get bounced because they didn't know it was a mod. So the suggestion is pretty simple. If the Server is using a "series" that isn't standard with AMS, a big *FLASHING* bar shows up in the Server Screen that makes it clear that it's a mod. Furthermore, below that there should be a link that the player can click on that opens up their web browser and takes them to a server to download it. And to make it more secure, make it so that it will only take them to pre-known websites, like racedartment.com or other places.
Another Possibility: When you get kicked out of a server because of a file mismatch, it shows you the link to download the correct one.
