Photoshop and Lightroom won't load anymore

I have an old imac and it still has High Sierra.  I got on my computer today to edit some photos and PS and LR won't open anymore.  It takes me to an Adobe login window, and when I sign in, it says I have a 7 day trial.  I have been paying for this service for years and everything in my account looks good, except that when I go to see what programs are included in my subscription, it says that the PS install isn't compatible with my device.  It sounds like maybe it doesn't like that I still have Sierra?  Do I need to upgrade to Monteray?  What should I try without messing with my computer too much?