There are two parts in your integration of GameAnalytics.
Once you've imported the asset into your project, you must first set it up as if you were like any Unity dev.
In the Windows menu (right before the last drop down menu on the topbar), you'll find "GameAnalytics >" then "Select Settings". There's a second option called "Setup Guide" which is self explanatory.
Don't bother with the advanced options yet (custom values, etc.).
Once it's done you will find in the same GA menu a final option at the bottom of the list to "toggle" Playmaker. It will allow you to use the PM actions that will then be available in the Action Browser under "GameAnalytics".
Note that with the data protection rules, you must first get your users' consent before initializing the GameAnalytics SDK (action "GA initialize").
Apple and Google only want you to display a Consent window at the start of your app. What you do with the consent after that is up to you and how you feel about the legal aspect of your activity.