Thanks for the suggestion. I’ve actually been removing and reinstalling mysql trying to get rid of MariaDB but the two seem to be joined at the hips.
I created the new db and user as given in your example, everything is installed on the same machine. When I tried the installer again it came up with the same error and created user oc_kachada1. I granted permissions to that user, flushed and retried and it created oc_kachada2. It wants to create a new user and connect with that. Is there a permission I’m missing from my mysql admin account maybe? How to check this and compare with root?
Life was so much simpler when we could just use root for everything 
If it makes any difference I’m on Debian Stretch