The Asset Bundle system is no longer supported by Unity and has been replaced by the Addressables System. To conform with these changes, the Asset Bundle Loader is no longer used by the Streamable Assets Manager. Instead, two new Addressable Based Chunk Streamers are offered, in addition to an abstract base Addressable Base Chunk Streamer class which can be derived from to implement custom Addressable Chunk Streamer classes.
Please refer to the dedicated Addressable System Chapter for more information on how to get start using Addressables.