Sync Square Product Library with Webflow Prodcuts

Goal
-When we get a new order in Square, automatically change the inventory in Webflow
-When we register a new product in Square, automatically register same info in Webflow.

Currently, we manually change the inventory and register in Webflow.

As far as I refer another article,
Square
Event: should be Watch New Events?
Sanbox: No
Permissions(Scope): All READ?

Webflow
Action: Update an Item Inventory?
Enter Item ID: by Selecting or Manual?
I have no idea how to configure Item ID

Sorry I am beginner of MAKE so please help me.