If one has more than one DB with the same name, running

astra db download-scb -f aaa.zip $DB

gives the error for the "Create database" operation, namely [ERROR] ALREADY_EXIST: Cannot create another Database with name 'workshops' Use flag --if-not-exist to connect to the existing database.

This message should be more accurate (and perhaps hint at the fact that you can specify a database by ID).