By default, Google Ad Manager doesn’t let you link a GA4 property. It will tell you that: The Google Analytics Terms of Service in your network settings must be accepted before this action can be performed. To fix this, go to Admin → Global settings → section Report settings and tick Google Analytics 4 property Reports in Ad Manager reporting. Be sure to fill in a Display Name at the top of this page if you haven’t done so already. Without it, you’ll get an error while saving the settings.