@Adrian We understand you are looking for customer information to help you fulfill a GDPR request.
The best resource to start with would be the Azure Data Subject Requests document as this will be able to guide you to complete the request.
It should be noted that we cannot provide individual guidance as some logging if turned on can capture client request IP addresses. We would not know if you have enabled this logging or what other custom logging you may have implemented into your application. As a result, following the above documentation is the safest path forward to ensure you perform your due diligence to complete the request.