When you running shell script of Install OMV5 on Debian 10 (Buster) on clean debian 10 install you get two errors. First you need install gnupg, to be able to addkey. Second you need to make oneliner of "apt-get --yes --auto-remove --show-upgraded \..." otherwise you get E: Sense auto is not understood, try true or false.
So this is not issue this is just how to solve it, if someone like to.