No offense to the other wiki contributor but his edits added numerous errors and a great deal of confusion to the wiki page I originally put together documenting the setup of FreePBX 15 on Debian 10.
A “clean” version before edits: https://wiki.freepbx.org/pages/viewpage.action?pageId=175178277 See update below.
In here I specify that you should log in as root or use sudo su - to get a root login shell, which would have saved you from the headache.