Using old Photoshop CS3 with new i Mac

I had CS3 working with the early Mojave version. However, when my iMac crashed I got a new one and couldn't get CS3 to work as I had to get another activation code from Adobe and they had shut down their activation server. Since it was not 64 bit I got the latest Photoshop Elements for Mac and that works nearly as well. About the only think it can't do is convert to CMYK.

So if you have to get an activation code from Adobe to use it I don't think you'll be able to.

CS3 is no longer supported by Adobe.

According to last announcement from Adobe, using old versions of Creative Suite is, in simple words, asking for trouble.