[MacOS] Calibre doesn't open

Calibre had been working very nicely. But I downloaded new version 5.8.1 on Macbook Air Big Sur. I moved .dmg file. Opened it. Moved Calibre to APPLICIONS and saw then it was transfered. When I tried to open it, I get the Calibre Icon on my dock. When I double click nothing happens.

When I right click, it gives "Options" (such as eep in dock), Show All Windows, Hide, Quite. Sometimes at the top t will say Application not responding.

I've gone through this process several times. I am not technical and am old. Hope you can give easy to follow advice.

Thanks.