I like this add on by FF doesn't one of the increasing number of add ons and websites not supported by FF

I don't know why IDM extension seems to work great in Edge Chromium, but fails to do so in Firefox. For example some sites just don't work when in Firefox, but they are fine in Edge. It says something about "encrypting" in Firefox... Encrypted sites showing in Firefox but not in Edge?? No way! What the heck is this? Please don't get me wrong. I love Firefox much more than I do both Edge and Chrome, That's why I am somewaht dissapointed about IDM malfunctioning in Firefox..