Thanks for the update. You can certainly use Site Kit on a subdomain without issue, using the full domain you referenced. Be aware that before migrating to your main top level domain (aivy.app) you’ll need to reset Site Kit, with the plugin registering the actual domain used during setup on the Site Kit service. For that reason if you’re not planning on using the aivyapp.wpcomstaging.com publicly you may prefer to setup Site Kit once your site is fully live and on your top level domain.
If you do want to go ahead and setup Site Kit on aivyapp.wpcomstaging.com now that this subdomain is fully accessible please attempt the steps below, which would rule out any plugins, browser extensions or theme issues impacting your site setup:
- Login to your site from a Chrome browser incognito window
- Install and activate the Health Check & Troubleshooting plugin.
- Navigate to “Plugins > Health Check & Troubleshooting > Troubleshoot”.
- From the same screen click on the “Available Plugins” tab at the top right and then click on the “Enable” option next to “Site Kit by Google”
- Attempt to setup Site Kit once more
You can exit troubleshooting mode afterwards.
Let us know how you get on after attempting the above.