Hello,
Even though my addon is compatible with the new Firefox for Android (code name "Fenix), Firefox team decided that they will allow installation only handful of addons (about 9) with a plan to support about 30 by the end of this year.
There is a huge discussion here:
https://discourse.mozilla.org/t/add-on-support-in-new-firefox-for-android/53488/7

They are planning to support all extensions eventually, but there is no estimate when will that happen.

However there is a partial workaround - my Cloud Dials page works in every web browser, including the new Firefox. So just create cloud account if you don't have one already and use the Cloud dials page instead.
Currently it's not editable, I need to upgrade my server which will take some time...
Also make sure to enable thumbnails synchronization on your desktop, then you cloud dials will look exactly the same on your Android.
https://group-speed-dial.fastaddons.com/cloud

Best regards,
Juraj Mäsiar