That might be cleaning out vacant apartments, picking up rent checks, unlocking a door for a showing, scrubbing toilets, whatever.

Marketing to owners who have the equity to pull off an ADU on their own may not be smart.Focus on a "first-mover" advantage that the owner can unlock "sudden, unrealized equity" that over time will melt away as more ADU is built.

Did he not knock first or did he unlock the door and walk in?

Just need to unlock to path!

If it's unavailable, tell your PM to wait until it is unlocked.

As others have said if you can't then you could just consider selling, that is a way to unlock that equity. 

I’m excited to see what possibilities this journey will unlock for my future and I look forward to networking/contributing with everyone in the BP community.

Any door should be unlock-able from the inside without a key, so people can escape in an emergency.

So I am not sure whether he is a Trespasser(broke in via unlocked window) or Squatter.What is the best way to proceed if I should buy the property? 

Sticking to my niche and doing what I know...add value and work within existing laws ala what @Daniel Gonzalez just mentioned.There’s gold here, just have to know how to unlock it.