Hi.
I believe that you should upgrade to PowerServer 2020 to be able to deploy a project from PB 2019 R3 to PowerServer. Also I do believe that Appeon PowerServer 2016 was compatible with PB up to version 12.6.
Unfortunately I don't know where you can find compatibility charts. I hope you are aware that PowerServer is a product that is obsolete and has nothing to do with powerserver in PB 2021+. If you have a paid maintenance for Appeon Powerserver 2016 you may be able to obtain an upgrade to the latest version (2020) that will work with PB 2019.
Andreas.
Andreas.