Metallum lyrics in local mp3

Hello, I'm new in the community. Can anyone tell me how can I add lyrics to my mp3 file (locally stored) from the site 'Encyclopedia Metallum'. Suppose I want to tag lyrics automatically to every mp3 of an album (the songs already tagged correctly before, just wanted to add lyrics, not artist/album/year).

There's a lot of lyrics collection of metal artists (main+underground)

I've searched the community relating to this but didn't find an specific and simplified answer.

You have to use a web source script.
Here is the link to already available ones, in this case Metal Archives:

Have a look around. If you do not find one for your source, you have to create one but perhaps the already existing ones will suffice.
Also see that there is a lyrics tool to tag all tracks of an album:

The metallum web script mentioned above doesn't feature lyrics adding.