If you see the above screen or message, it is likely you have an ad blocker preventing the normal functioning of the app.
If this is the case, then whitelist the app’s domains in the ad blocker’s configuration to continue.
The domain you may need to whitelist for Google Analytics in Confluence is:
www.gaic.app
If you do not have an add blocker, then sometimes Confluence fails to load the app. Wait a few minutes and try again. If this fails, contact support.