Dead link now. Would like to know myself. Just got a server a few days ago and can't use it without being able to upload custom maps. Ftp doesn't work, nor does the servers control panel uploading.
Think I got it figured out.....finally. But now my server isn't listed.... Might be the migration.
The lack of changing the server info in the ServerGrid.json file is probably my issue. When Tallon said all you had to do was drag them over to your server through FTP...... figured that was it. Looking at the first few lines in the .json file show server info, but it appeared to be generic. Had seen a few other posts mentioning needing to change the server info, but they were several months old. Thinking the generic lines might part of the dynamic setup... you don't need to add that info now. But you do.