The setting for this addon only contains one option to enable or disable it.
When enabled this will reflect changes on WooCommerce checkout page by merging Phone Number field and Account Mobile Number (digits field) when the user is not logged in or in the case of signup process at checkout, in this case billing phone number will be feeded the data from account mobile number (digits field) for that particular order. For all consecutive logged in order user’s will get an option to change their billing phone number.