Older Edition of Photoshop

Hi all! 

I am in quite a pickle! I currently run a 2011 Mac that runs El Capitan (10.11.6), I know, I know. I had an error with photoshop and uninstalled to reinstall, but in doing so I only has access to Ps 2019, which of course is not compaitable with my laptop. 

I spoke to tech support and they said there are no older version (2015) that they can direct me towards. Is there anywhere you can direct me?

Thanks!