When Flex Sync is not configured, the Axsy Field Service Mobile App will sync data using a default syncing scope.
The app has been given a default priming depth of 2. This means that from the Service Appointment (the root Object of the app's priming "graph"), we will prime the next layer based on the "Parent Record" field of the Service Appointment. This should be either a Work Order or Work Order Line Item.
Related Lists and Fields
The Related Lists that are synced to the app are dependent on them being on the Page Layout of their parent Object. Fields for Objects that are part of the priming graph will be synced to the app regardless of whether they are on the Page Layout of the Object, but should be added where needed to ensure they are displayed to the user. Navigate to Setup > Object Manager > Object > Page Layouts to configure Page Layouts.
Flows that are primed to the app need to be in App Extensions under Field Service Mobile Settings (Salesforce Setup).
Quick Actions that are primed to the app need to be added to a record's Page Layout under the Quick Actions in the Salesforce Classic Publisher.