I too confirm that installing a trial of Adobe 2020, and then starting Acrobat 2017 allows you to register Acrobat 2017. After that you can also delete Acrobat 2020.
Apparently the Adobe Licensing app is a single specific app which is brought in by the Acrobat XXXX installation; and a more recent version of the Licensing application works well with older Acrobat versions.
I too confirm that installing a trial of Adobe 2020, and then starting Acrobat 2017 allows you to register Acrobat 2017. After that you can also delete Acrobat 2020.
Apparently the Adobe Licensing app is a single specific app which is brought in by the Acrobat XXXX installation; and a more recent version of the Licensing application works well with older Acrobat versions.