How do you work in a team?

Hi,

Since past 2.5 years, I have been working as a solo web developer for a company. I do have in-depth knowledge in Front-end Development using React but I lack is experience of working in a Group.

So there's a great offer for me, where I will be paid to help solve bugs in Angular by a firm.

What I want to know is, how do you work remotely in a project with a company? I am aware of git and few concepts like branching and merging and can work on it.
But that company won't give me access to whole project but a small segment I guess then how do I make it work?

It may sound too dumb for you but will be big help for me.