We recommend using the Google-provided Gmail app instead of the Apple Mail app.
After you download it, follow Google's instructions here: https://support.google.com/googlecloud/answer/10635784?hl=en
Third-party email clients are not supported by UC Berkeley.
If you do wish to configure Apple Mail, see https://support.apple.com/en-us/HT201320
If you have further questions, please contact the vendor of your third-party email client. UC Berkeley bMail accounts are standard Gmail accounts, so any instructions you find referencing Gmail should work with bMail.