Creating new Project in Books from CRM

Creating new Project in Books from CRM

Hello all,

I have used workflow rule in CRM to create a new Project in Book when a Deal is won:
- Rule creates webhook when deal is 'closed as won' 
- Flow takes payload and creates new project in books

My issue is the customer. Books wants the 'customer ID', which does not seem to be the same as the 'Account ID' from CRM. How do I get this information into Books?