Developer reply by Ysard
Rated 5 out of 5 stars
Works fine on Thunderbird 60.2.1, thanks!
ps. But i couldn't find it on search, had to install in manually "from file".
In fact, as long as the addon has not been verified (it's been 3 weeks), it does not appear in the search results of the site.
To create your own collections, you must have a Mozilla Add-ons account.