Okay, I left a comment yesterday, but it’s not showing up today. So I’ll re-write what didn’t show up for some reason.
I figured out that because I had also, a long time ago, attempted to use a different method (from Linux Mint - Community), I had the wrong GIT repos, and even though I was following A new, community-hosted Unreal Engine Wiki - Announcements - Epic Developer Community Forums during this situation, my GIT repose were incorrect, and I was using version 4.7 – not 4.13.
So, all this stuff can be considered resolved for me. I don’t want to delete this post though incase anyone else runs into the same problems.
Deleting the contents of the UnrealDirectory and starting over got me past all these issues.