Unfortunately, Polar does not currently allow connections with their app. We are working in order to have access as soon as we can.
However, you can still sync your Polar activities through Google Fit or Apple Health and make the most of WeFitter.
How to connect through Google Fit:
Open Polar app and go to your settings
Connect with your Google Fit account.
Come back to WeFitter and connect with the same Google Fit account on your connections page.