How do I manage a player with autism who is at times disruptive? [on hold]

I recently gained a new player who has autism and he is making it harder for me to make my campaign. I have never dealt with any like this and I don’t know what I should do regarding his disability. He sometimes has breakdowns when the other players do something like make a loud noise and no one really knows what what else will set him off. I’d feel like a terrible person if I got rd of him and when he does contribute the campaign moves along nicely. I don’t know whether to make rules for the group to follow or not.

How can my character seed a thieves’ guild with out being disruptive to the rest of the group?

Background: D&D 5e with a steam punk flair.

My protagonist is a changeling rogue (can assume the role of other people) with a small bit of magic (Arcane Trickster). My deity has requested that I seed a thieves guild to act as a network of spies that will slowly grow as the protagonist progresses in their adventure.

I have another question in world building about how to go about this story-wise. In this question, I would like to focus on how I could go about doing this without being disruptive to the main storyline, or others at the table. I want to do this for fun, but not detract from the fun others are having.

On Page 186-187 the PHB discusses “Between Adventures”:

Between trips to dungeons and battles against ancient evils, adventurers need time to rest, recuperate, and prepare for their next adventure. Many adventurers also use this time to perform other tasks, such as crafting arms and armor, performing research, or spending their hard-earned gold.

In some cases, the passage of time is something that occurs with little fanfare or description. When starting a new adventure, the DM might simply declare that a certain amount of time has passed and allow you to describe in general terms what your character has been doing. At other times, the DM might want to keep track of just how much time is passing as events beyond your perception stay in motion.

While this doesn’t explicitly talk about seeding a underworld super cult that you will one day use to take over the world, I think this would be the appropriate place for this activity so as not to be disruptive. What I don’t know is how much time/money investment should go to this.

I remember reading about player housing / guild halls in one of the official D&D books, but for the life of me I can’t find it at the moment.

How can I do this within the rules of D&D 5e without being disruptive to the existing game?