This typically happens when pop-up blockers are being used:
- Clear your browser cache and cookies.
You'll need to visit your web browser help page for instructions on how to do this. - Temporarily disable any pop-up blockers, ad blockers, and allow popups for the https://www.rocketleague.com/activate webpage
- Log in to https://www.rocketleague.com/activate and switch your primary platform as desired.
- Start the game at least once on the platform you selected as primary.