Rated 5 out of 5 stars

le Lincky ar Samh. 14, 2017 · buan-nasc

It's really a regret of the discontinued support in the latest Firefox,

Alternative workaround,

1. Install Total Command (TC)
2. Download MAFF plug-in (decMaffWLX 2015.03.21) at https://totalcmd.net/directory/lister.html
3. Open TC and browse the zip file, double click, and prompt to install

Note, you can' directly open maff file by TC, the steps is to locate the maff file and click F3 or View to load the UI.