If you've followed the set up instructions fully, then I'd imagine it is a problem with the license.
I believe A/B testing is an Enterprise tier feature, so using Base/Ultimate is probably the problem.
If you're a Kentico Partner, you can generate development licenses here https://partner.kentico.com/Benefits/Development-license, if you don't have access to that you can maybe contact the Kentico Sales Team and they might be able to provide an evaluation key.