As noted in this post, you need to change a line in pg_hba.conf to “trust” instead of “md5” (no quotes) to be able to batch create tables. Note this is only for testing purposes and not recommended for production. The only reason is because I am running some benchmarks for web2py. I want to be able to create the database itself from within the benchmark script and not have to create it each time.
Unless you set up your database access with the “trust” option this prompt is probably asking for your password, not the password for the username you passing to the createdb command.