Hello mriguero,
You came from the best resource for your issue with app tracking: If an app asks to track your activity
If you can't turn on the "Allow Apps to Request to Track" setting
In some circumstances, the "Allow Apps to Request to Track" setting can't be turned on, including:
* For users with child accounts or who are under age 18 by birth year, signed in with their Apple ID*
* If your Apple ID is managed by an educational or business institution
* If your device is managed and uses a configuration profile that limits tracking
* If your Apple ID was created in the last 3 days
While this setting is turned off, each app that requests to track is unable to access the advertising identifier (IDFA). If the status of your account or device changes and you then choose to enable “Allow Apps to Request to Track,” the app's next request to track will display the permission prompt to you.
* Child account age varies by country and region.
If you are within a region that the child account age is over 18 and still get this error, then it may be best to contact Apple Support directly: Get Support
They'd need to take it from here.
Cheers!