According to Article 27(3)The Data Representative is:
Nominated by the controller or processor to be addressed in addition to the controller or processor (by EU regulatory bodies)
Established in a member state where you process personal data (or monitor behavior)
They can be a natural or legal person based in the EU, whom the EU or relevant GDPR supervisory authorities can contact for any issue related to your data processing.
This regulation applies to the processing of personal data of data subjects who are in the Union by a controller or processor not established in the Union, where the processing activities are related to:
The offering of goods or services, irrespective of whether a payment of the data subject is required, to such data subjects in the Union; or
The monitoring of their behaviour as far as their behaviour takes place within the Union