Your Google Drive password is unrelated in this issue. Codebook uses a master password to secure your data locally. When you backup your data via Dropbox or Google Drive, a replica of the Codebook database is stored in the cloud. In order to restore that replica database, the password to access the content of the database replica must match the password you currently use to access Codebook. Can you confirm these two are the same, it appears from the response you are getting when you attempt to restore that they differ.
If you are still unable to perform the restore from Google Drive, Apple includes instructions for restoring from an iTunes backup here.