Linux is so userfriendly, so the rpm that can be downloaded is missing dependencies. However, I’m quickly becoming a fan of zypper and OpenSUSE’s dependency handling, and comes to the rescue:
sudo zypper in cryptomator.rpm
Even though cryptomator made a mistake in signing part of the application, it can still be installed by pressing ignore. Are you sure you want to do that? It seems a bit crap for such an essential utility.