@rhweinberger "normal" mode in this case was recovery mode. I had just erased the "Macintosh HD" partition because it was just full of crap and I wanted a fresh start. On the screen where you log into your apple account, that's where you'll find the "Erase Mac" option. I don't know if you have to do it before or after you sign on, but you should not exit from the dialog after you sign on. The option is on the menu bar at the top of the screen. Good luck!

Just had this happen to me and noticed your question during my search. I was able to fix it by allowing it to boot into normal mode where it asked me to use my apple account to activate the mac, before I "quit recovery assistant" button (IIRC that's what it said) I chose "Erase Mac" from the menu up top. That took a few seconds, rebooted and I was able to continue a fresh install, this time without the “No users available for authorization” message.