firfox 47.0 (German Version) add on avast passwords

Avast Passwords Avast EasyPass
1

avast passwords xpi is installed but not activ on firefox surface 47.0 (German Version)

avast program shows firefox browser as not installed
any idea please

2

Is it a Surface Pro or a RT ?

3

avast 11.2.2262 free updated newest version, firefox free 47.0 on win 10 prof