Hey juriggs, welcome to the Community.
Only customers with HubSpot Marketing Basic/Pro/Enterprise access have access to the Domain Manager (here, under Available for) in order to connect a Domain to HubSpot.
Would you be able to send me a screenshot of your team's current subscription to HubSpot(https://app.hubspot.com/account-dashboard/l/)?
My team's subscription is the Marketing Starter. I would like to add an email sender domain so that our emails do not get filtered out by spam filters. What are the options to do this?