Later versions are alright, but may be unstable (since I'm not using them day-to-day myself). It's a good idea to stick to unity's Long Term Support releases as they're less buggy.
NB: If using a later unity version, you will need to remove the "Visual Scripting" package in the package manager.
Save early, save often - Backup regularly, or (ideally) use version control like SVN or GIT. Something will sooner or later trash your files or scripts ;)
Download PowerQuest
Click "Download Now", then "No thanks, just take me to the downloads", to get it for free.
Creating a New Project
Set up PowerQuest in a new project:
Open Unity hub, click NEW. (Select version 2020.3 if you have multiple versions installed).
Choose 2D, select a project name and location, then click CREATE.
Once unity loads, double-click the PowerQuest .unitypackage you downloaded from itch.io, and click Import on the window that pops up.
A PowerQuest window should appear shortly. Dock it where you want
Choose a template to start with, and hit the Set it up! Button.
Run the demo game:
Hit the play button in the unity editor to test the demo game. Press the stop button once you're done.
Hit the Scene button next to the Forest room in the PowerQuest window.
Hit play to test from that scene.
Now dive in and start changing stuff, and adding your own.
You can delete the template stuff later. For now use them as an example and starting point.
Find Help
View the Editor Documentation pdf for instructions on using the editor. (Note the Screenshots in it are a bit out of date).