I recently acquired a newish iMac wth a new Fusion Drive, (2TB) and a fresh install of OS 10.14.6 Mojave. I needed to install Adobe Photoshop elements 2019 which I had been using on another iMac, (My Wife's). I located my serial number and activation code from my Adobe account and proceeded with the download. All went well. When I tried to open Photo Editor a window kept popping up saying that the there was an error with the download. After repeating the process several times and finding no other help on the Adobe site, now with steam coming from all parts of my body, I decided to open the Adobe chat window. After explaining what I had done and answering a million questions, I gave them permission to remotely interrogate my Mac. After watching their cursor navigate my screen for a couple of minutes, I was asked if I had ever dowloaded and installed Adobe Creative Cloud. No, I replied because I don't want it and would never use it. OK said the tech, you will need to download and install it, even if you don't want it just leave it in the applications folder.They signed out and off my Mac so I downloaded and installed Creative Cloud then Downloaded Adobe Photoshop Elements and guess what. PSE Editor worked. This may or may not apply to Photoshop and or CS3 or what ever but give it a go.
Good luck and please let me know if it works.
