Developer reply by Florent Tassy
Rated 2 out of 5 stars
Using Thunderbird 115 on Ubuntu Jammy. Add-on installed OK but unable to log into WhatsApp. I got a"Browser Unsupported" error message when I tried,which showed a set of icons for suggested alternative browsers.
After an hour it started working properly and let me log in. All looked good but the next time I tried to log in, I got the perpetual spinner. There is clearly something wrong with this add-on at the present time.
I am sorry that you experienced issues with the add-on. Since there are more than 3300 daily users of it, it seems that there is clearly something wrong with your system at the present time. There are several ways to get support, I encourage you to use them to find a solution.
To create your own collections, you must have a Mozilla Add-ons account.