ios: why doesn't an iPad connect to an iMac (via a lightning cable) to synchronize, after following all the `trust` steps?

When trying to connect a new iPad (iPad Air, third generation) with 13.3 to an older iMac with MacOS 10.11.6, the iPad / computer (cable) connection is never successful.

All indications are followed correctly:
Trust This computer is selected.
Do you want to allow this computer to access this iPad? Yes
The password was entered correctly on the iPad.

Then the computer simply hangs on the indicator
To allow access, please respond on your iPad...

… until the waiting time with a response from
iTunes could not connect to this ipad. You do not have permission.

What's wrong? Apple has not intentionally allowed the use of old computers / MacOS with newer devices?