I can't use grammar and spell on software called "emailmapp"

[arianed-oss]

helo
i like your software called "emailmapp"
I've downloaded extensions from this page :
https://addons.thunderbird.net/en-US/thunderbird/extensions/language-support/?sort=popular

but I don't suceeed to install xpi files on your software (even if I have extracted them)
and it's very unpleasant to create emails when I can't use grammar and spell :(

can you help me to install it please ?

I than you beforehand.

BR,

Ariane