Server won't start.

I recently got a server from Aternos, and almost everytime I tried to start up my server, it would not load. It would say starting for about 4-5 minutes, then say stopping and go offline again. I have downloaded DecoCraft and also put in one of my custom maps. I've tried getting rid of the mod + map, and it still doesn't load. My friend got a server to try it but she got in when I was attempting to join and I also waited a few hours. I also have no plugins downloaded either.