If you want to use your Google Workspace and send emails properly, you will need to set up MX records for your domain.
WHAT ARE MX RECORDS?
MX Records point to a Google mail server and make your email work.
WHAT DO YOU NEED TO DO?
You will need an access to the DNS zone on your domain. Then you will have to:
1) Find your DNS records
2) Set up the MX records for Google Workspace
3)Tell Google Workspace to activate Gmail
After you sign in to your DNS, you should add a couple of MX records in TXT format:
It will take some time after saving each MX record to propagate these settings, so do not panic if it does not work immediately.
For further information please follow the steps in Activate Gmail for Google Workspace.