Consider https://filen.io/. It has great Linux support (also speaking from experience). The free option has 10GB, which might be more than enough if you just need storage for documents.
I especially enjoy the “Mount as drive” option. It basically lets you set a mounting point in a directory of your choice, and then you can simply use your normal file explorer to do all the things file explorers normally do within that mounted directory, as if it were local storage (but it’s not).