One of the strongest features of the SharePoint Connector is the ability to dynamically build a folder structure based on data in Business Central.
There are two main mapping principles:
- Name (Number)
- Reference No.

Name (Number)
Name (Number) is used for master data like Customers and Vendors. You specify what two fields are used to build out the folder name.
Reference No.
With Reference No, the folder is created from a single field. This is usually used for transactional SharePoint support. You can use Document No. or Order No. fields (or similar) to create documents attached to a specific transaction.
Be aware, that a Sales Invoice No. is not the same as Posted Sales Invoice No. making Order No. a better field to use for sales and purchase documents since it remains static across posting. (Alternative use the Posting No. field on sales headers).
Parent Table
In the screenshot above, Job mapping is specified with a Parent Table. In this case, the Jobs folder will be created as a subfolder to the Customer.

Use 2 levels of Folders
This is a special case, giving support for custom tables with primary keys with multiple fields. See Adding SharePoint Factbox to a new table.