You can download your world but using this following guide below
How to Download a World from your Server
Command: /dl world (world name)
Simply type the command in-game and insert the world name where it states to above. If you don’t know the world name, you can figure that out by using the /worlds command (requires op) in-game.
Still a bit confused? Check out this video that also explains how to download your world!
https://www.youtube.com/watch?v=1DcfYlre6AA