App specific password and Edison mail at an impasse

First, I have created app specific passwords before without a glitch; I know what they are for and understand the idea behind them.

I subscribed to Edison Mail (which was not cheap) and installed it on my Macbook Pro and on my iPad Pro as well. Then I started adding my many email accounts. This is the feature - the single inbox -- that attracted me in the first place. It all went well until I tried to add my @mac.com address.

EM seems to need an app specific password, so I went to that screen, typed in the app name and hit 'go'. I've tried this many times without getting any farther. The process just stops once I hit 'generate the password'. Instead I get the message you see here. I can go to the settings pages as requested, but there's nothing there to see.

Can some kind soul point me in the right direction? I am generally pretty quick to follow the tech end of things, but then I wrote my doctoral dissertation when Word was still toddling around, in 1986.

PS. This question is about more than one device, but I was forced to pick one alone.