@peterlockett Okay, I followed your instructions and they went to the same page I went to originally. It says it will run on 10.13 but it doesn't and I've gotten two responses saying Opera just forgot to update that piece of info.
I am trying to tell you that a current build of Opera isn't going to run on a Intel Core i5. It can't run anything newer than High Sierra. It doesn't have the right hardware. I already have an obsolete version of Chrome that "works" but it isn't secure. Don't need an obsolete version of a Chromium-based browser.