How to connect my Google domain email address to Dub

Hello, I’m new to dub trying to get my first email campaign running. And let me apologize beforehand if this is the wrong form for this question. I have connected my Gmail account to Dub however it is not the email address I want to use for campaigns. I want to use my business domain email address which is also been forwarded to my Google Gmail account.

Example: my Gmail email is workwithsea and my business email is ensure@ . I’m searching online Google and YouTube for answers and I found this which I’m not sure if it is the answer to my issue. I seen a YouTube video The spoke of some kind of redirect using short.io. And I have an account there as well. However I’ve sent countless chat and emails to dub support that this point are piling up with no reply. Would someone be willing to give me some advice or a way forward.