Any transactions in Xero that you import into ProRata that have Tracking Categories attached to them will also be pulled into ProRata.
Subscriptions
Tracking Categories will be attached to each subscription. You can view this on the subscription detail page.
Journal Entries
Journal entries that are pushed to Xero will also have the same Tracking Categories attached to them.
Reporting
In certain reports you can choose to view Tracking Categories by selecting them in the field chooser.