LR Classic v12 won't install

Hi, after using Lr5 for many years, I saw what LrC v12 offers, so downloaded the trial.

After installation, it showed V11.5, so I looked at the Updates page and it says v12 is not compatible. I am on a 2018 version Mac Mini running Catalina (OS X 10.15.7) with i7, 16GB & 512GB SSD.

The Adobe site says v12 only needs a lesser OS X than what I have, so why won't it let me install v12?

Cheers, Malcolm