1 Login to the Kinetic Panel and Stop your server.
2 Go to the File Manager
3 Navigate to saves > worlds_local.
4 Right-click on your desired world folder, and click Download.
Valheim guide
How to Download your Valheim Server World
Valheim server owners may wish to download their servers worlds to keep a backup, find their seed or to play on single player. This can easily be done by finding the world.fwl file.