Downloading world with builds and items

Is there a way to download the server world with the items you have and your builds? I've got a server in Aternos and i'd like to update it to a different version, but i can't because it's gonna clear my world completely. If i try to download it, all i'll get is the world i started with, no builds nor items i had. I tried backing it up and downloading it then, but when i try to play it in singleplayer, the builds and items aren't there. I remember i tried to do it once and it did download them as well but now it doesn't. Any help?