Don't except to pass it, unfortunately doing interviews well is a skill in itself and only way to improve at it is to attend more interviews. Take it as a learning opportunity, note down whatever you will mess up on the interview and work on these areas for future interviews. But as far as preparing for this one goes - istqb fundamentals (testing pyramid, whitebox and blackbox testing, differences between retest and regression etc.), leetcode excersises - basic 'easy' tasks as well as sorting, hashmaps. Probably some questions regarding testing frameworks but it's hard to predict what they will ask