How can I use a vault for 1&1?

Help Desktop App
4

This says it’s compatible with Win10.

https://m.hilfe-center.1und1.de/tarifoptionen-c85328/1und1-online-speicher-c84531/einrichtung-c85547/systemvoraussetzungen-1und1-upload-manager-a787741.html

Although I’m not an 1&1customer, I am pretty sure one of the biggest provider in Germany offers state of the art software