I’ve tried to install my add-on from AMO but download got stuck:
That’s what I see in “Extensions” tab:
Checked on 2 devices. The same add-on build (.zip) works ok in Chrome from its Web Store and when using local via “Load Temporary Add-on”.
I tried to install your add-on and failed as your snapshot.
And I have the same problem as you and don’t know what to do.
Here’s my add-on.
So I’ve tried the same with yours and got that result again.
It’s ok now, both add-on can be installed properly. Don’t know why.