In order to install Google Analytics 4 you need to provide its measurement ID from your Google Analytics 4 dashboard and paste it to this field:
Attention! If your GA4 account was created using the Setup Assistant in the GA UA’s admin section or automatically by Google, it may not work correctly. Please create a separate GA 4 account and use its measurement ID. If you still want to try, please disconnect it from GA UA and don’t allow Google to automatically create another GA4 account for you
This video explains how to find Measurement ID.