Play FTB offline with twitch?

I would like to know how I could play the ftb packs offline, so without twitch, the old launcher does not connect anymore and I have no idea how to install Forge. Would be nice if you could help me

Has done, now just use the Technic launcher

And why do not you just use Twitch? Click on Install and then start is not harder.

I just want to play the pack offline, and Twitch does not seem to see it as possible to play modpacks offline because they want to sign in offline, but that's not possible because MAN IS OFFLINE