LR 6 not working anymore on Catalian 10.15.7

Hi there, back in 2018 I purchased LR 6. I have been using it with no issues on my Mac Os Catalina 10.15.7. However since 3 months LR does not work anymore on my Mac. It does not start. I do not want to purchase a plan. Does anyone have a solution to this ? Cheers. Paolo