Bitwarden does not support Single Sign On. This is by design for security reasons. You must create a new password for your Bitwarden account.

By default, open registration is enabled. This can be changed via the config variables by editing /app/data/config.json using the File Manager. For example, to disable signup but allow invitations set the variables as below:
"signups_allowed": false,
"invitations_allowed": true,
Note: We provide this configuration by default (for security & privacy reasons).