How to complete the mission \ "General gathering \"? (Fallout 4)

AntonToxa
Where you run, in one of the settlements, put in the sky from the rocket launcher,
which the minuteman gave. Or did you throw it out?

rosomaha7 Flare
Launcher? Which one?
rosomaha7
I don't have a rocket launcher in my inventory

AntonToxa Shoots
Red. Really not given? 15 charges go to it.
Ask the minuteman with the lazar weapon.

AntonToxa
Here's one.
Spoiler

I don’t want to create a topic))) the question is ... if I join the BS then I can join the institute or not? otherwise the quest weighs on the BS and xs what's next with it

Domian83
This is the first time I see this))

AntonToxa
Then here's her ID: 001E7DA3

Domian83 ATP
Bro! I entered Player.additem 001E7DA3 1 into the console and nothing happened.

You just have to come to the castle and talk to Gavri