App Store no longer downloading or updating apps on Mojave 10.14.6

Today I bought a new app on the App Store but I am unable to download it. The "Get" icon turns into a spinning wheel and just turns and turns. When I quit App Store and restart the "Get" icon has turned into a cloud icon but I am still unable to download. I am also unable to update other software on my iMac (Retina 4K, 21.5-inch, 2017) I have tried lots of suggestions from the internet but nothing helps

I notice that many people have had this issue. What's going on? Can someone tell me ho to fix this without updating my OS?