People have to keep downloading on my server.

When people join my server, they download some files. When they rejoin, they re-download stuff they already have. Is there any way to fix this?

FastDL server may not have the file on it. Most web servers are very strict on file names, when you add a new resource file it should match the exact file name that will be on the FastDL server. This includes upper and lower case letters in the file names.