Some out of the box standard Microsoft entity maps serve as prerequisites for few of the A365 entity maps. Before starting the A365 entity maps, we need to do a few things. 

Customers and Parties

The customers and parties need to be running in order for some of the entities in the Device management solution to run.
 
Please follow the instructions from Microsoft that can be found here https://docs.microsoft.com/en-us/dynamics365/fin-ops-core/dev-itpro/data-entities/dual-write/party-gab#setup

Walk through steps 1 - 12 as suggested. 

In step 12, the last 3 entity maps (CDS sales quotation header, CDS sales order headers and Sales invoice headers V2) can be skipped as they are not needed for the Integrated Service Process
Also note that when running the entities in the list, make sure to run with initial sync. All related entities should also be started.

Workers

The Workers need to be running in order to sync responsible worker on the Service order.
 
Main entity:
Worker
 
Other entities:
NA