it was my impression that, when a new vault should be created, Cryptomator offers a couple of automatically detected folders.
However, for me (1.5.?) it only let’s me choose a custom location. Nevertheless, I’m using Google Drive, Dropbox and OneDrive, which work fine when I select manually.
All right, that’s not so easy to “fix”. Cryptomator would have to check the settings (or something like that) of each installed cloud storage service. That’s a feature request then, which you can create here: https://github.com/cryptomator/cryptomator/issues/new/choose