If you are on the Max plan, you don't need to do anything to activate Super Batch Mode. The Batch Mode you see in Photoroom is Super Batch Mode.
To learn how to use Super Batch Mode, follow the instructions in the various Batch Mode articles, including:
Super Batch Mode has the same features as regular Batch Mode and works in the same way. But it is much faster, uses the best AI model, and supports larger batches of images.
Further information
To learn how to upgrade your plan to Max so that you can enjoy the benefits of Super Batch Mode, see: