Joining the Institute faction and completing its optional quests is as easy as it gets.
How to Join The Institute Faction
The first thing that you need to do is to reach the point where you can complete the Main Quest called Institutionalized, find Father, and comply to his request.
Once you have successfully done it all, you’ll able to join the Institute and complete optional quests offered by it for as long as you wish.
There is a little catch, however!
Do note that as you progress to complete the optional quests offered by the Institute, you will continue to negatively impact your relationships with other factions named Brotherhood of Steel, the Railroad, and the Minutemen.
This is all you need to know in order to understand how to join the Institute. If there is something else you would like to know, make sure to let us know in the comments section below!