Start by clicking SENDERS in the main menu

On the Senders's dashboard click ADD SENDERS button

This will open a wizard that will guide you forward depending on your email service provider (ESP) and connection type.

Continue the tutorial by selecting your ESP
Connect Google Workspace using oAuth (Recommended)
Connect Office 365/Outlook using oAuth (Recommended)
Connect any SMTP/IMAP email providers
Connect Gmail using App password