You need to have a paid judge.me plan, in order to use their API key.
First, lets get the API key from Judge.me.
Open Your store dashboard, go to Apps and Open Judge.me.
Scroll down, you'll see Developers, Click on it.
Now, Copy the Private token and go to super rewards Dashboard.
Here, under Integration section, you'll see Judge.me, Click on it.
Enter the Private token, you copied earlier.
Then, click on connect.
Now, update the rewards settings as per your need and you're ready to go!