This is the latest patch which includes v4.8.15 of the plugin.
https://dl11.pgmusic.com/support/mpatch/bb2022_mac_update_build611.pkg

This version of the plugin does not require Rosetta to run so please test again without using Rosetta.

It sounds like the plugin does not have access to certain files and folders that it requires. To fix this, you can open "System Preferences->Security & Privacy->Privacy Tab". In the left pane select "Files and Folders" and then find Band-in-a-Box DAW Plugin Standalone.app. Make sure that "Removable Volumes" is checked. This should allow the Standalone app to work correctly.