I just did a new fresh install with a new prefix, and it was able to install a new version just fine.
So then I updated the config of the new install, and pointed it to the old db prefix which seems to work, although I get a login error.
I then updated the old install to use the same database config, and same thing, unable to connect to the db, so I am assuming the old version is just to outdated considering this is on php 7, old server was probably php 5.6