I figured it out - user malfunction on my part, I wasn't cloning nodebb into the correct "node" user home folder properly! Stooopid I know...
Extra to note - I also ran into failed setup when using nodejs 12 and nodeBB 1.12 (think hey lets go with the latest of everything!) and this was after correcting my user folder error, so decided to revert to a nodejs 11 and nodebb 1.11 stack.
The forum has successfully rebuilt and restarted, no errors and the plugin is doing it's thing!
Starting v0.3.0, NodeBB will require a third party emailer to send emails on its behalf. This plugin allows NodeBB to use the PostageApp service to send emails.
npm install nodebb-plugin-emailer-postageapp
Be sure to activate the plugin in the admin panel and set up the proper API key.