You should first make sure you do not have a CalNet ID. If you are in the directory you should not have a guest account created for you. Instead, you should use your CalNet ID and passphrase. Having a guest account created will cause problems.

If you are not in the directory, you may ask the site owner to create a guest account for you. Once he/she does, you will receive an email with a temporary password which you can change. You can also add your first and last name to the guest account by going to the My Workspace tab and then clicking Account.