To have the summons follow you, you need three things:

- the cultivation level has to be to the point where you can see the cultivate tile that says "activate summoning function"

-you will need either 10 or 20 contracting scrolls depending on what is required

-you need the contract scroll of the summon you want like lightning tiger king summon scroll (this does not apply with some purple summons which only need 10 contracting scrolls)