The fans on my MacBook Air kicked on soon after and ran constantly (just running it without importing and of my photos!). Ran the LR Classic installer and began kicking the tires on it. I called Adobe to inquire about LR Classic ($9.99 per month subscription) and ask if my LR6 perpetual license or software would be impacted and was told no, it would be fine. I called Apple and inquired about downgrading to Mojave on the Air 2020 and they said it was not supported and had to run Catalina or future macOS versions. I did a complete Catalina reinstall, ran Migration Assistant again and the same thing occurred. it would not launch and the logs indicated sandbox security errors. I exited gracefully and tried to fire it up later on.

Unfortunately, I ran into issues with LR6. I purchased a 2020 MacBook Air i7/16/512 again fired up Migration Assistant to bring over all of my data last week. Newer (2020) hardware can be problematic.

While it is not 'officially supported', it should also work for you. I used Migration Assistant to bring Lightroom 6 over from my old 2012 MacBook Pro to my 2017 MacBook 12' which I eventually upgraded to Catalina. There is no other way to 'install it' directly on Catalina due to Adobe's awesome move of shipping a 32-bit installer with the 64-bit LR6 application :| Assuming you are using cameras that have LR profile support, Lightroom 6 perpetual brought over to Catalina remains a viable option. as they have also a nice license policy which allows cross-installations on three devices.I also posted the following on The Lightroom Queen. So - if you have no 'exotic' raws (like me with Hasselblad) then you should give Excire Foto a try. ACDsee can 'look through' subfolders and bring a all previews (as Lightroom does is) but Excire can do this easily and damn' fast. ACDsee studio recognizes my Hasselblad raws on my Mac and can display a preview, recognizes these raws on Windows but cannot display a preview there. What I see is that the search in Excire is incredible fast and a great DAM / photo organizer - but Excire doesn't recognize my Hasselblad raws neither on my Mac, nor an my Windows machine. I am struggling on my Mac which is due to I am on M1 - and plugins are simply not working anymore in Affinity Photo (which is poor, but another topic).

Right now, I am giving ACDsee Studio and Exile Foto a try - either an my Mac and also my Windows machine. I have tested several app in the meantime.

Lightroom 6 catalina