Experience of development on AEM ,knowledge of OSGI/Apache Sling Should be flexible enough to do QE for the product, which includes writing Automation /Manual/Load Testing, etc
Candidate with Java server side knowledge is what we are looking for. If he/she has done automated integration tests before then it will be great. If not, then they need to be open to learning it and doing it, but then we expect him to be very good on development side.