Photoshop 2020 no longer working properly - no time to waste - where can I get cc2019?

Hi,
Since downloading the latest version of Photoshop cc 2020 yesterday, I'm now getting all sorts of error messages, not least a 'scratch disc full' message, even though the scratch disc ain't full! *&^!
I'm in the middle of an urgent project - trying to run some droplets - I don't feel like fiddling around for hours trying to get cc2020 working.
Does anyone perhaps know how I can go back to cc2019, which worked perfectly.
Does Adobe have a link for it somewhere?

Thank you!
Mark
ps running a 2013 MacbookPro with Mojave.