Yes it is. That command is to see if the PostgreSQL service is running and with nothing returned it looks like it is no longer running/installed. You can follow
this tutorial to uninstall what's left however you should note that some of those steps in the tutorial may produce something like "not found" - it's likely that will be OK but don't skip any of the steps. This also means you will need to start a new database and reimport your hands. Once PostgreSQL is fully uninstalled you can manually download and install PostgreSQL 9.3.15
from here. Using a Mac administrator account or administrative privileges install that PostgreSQL and for the password boxes use "dbpass" (no quotes) which is what PokerTracker 4 uses by default. Once PostgreSQL installs successfully reboot your computer and then try PokerTracker 4 again.