Here is a guide to help you add a footer to the bottom of your emails in Google Workspace
In your gmail press the cog in the top right corner of your screen.
Choose manage this organisation.
You may then need to input your password in again for your account and once logged in please visit https://admin.google.com/ac/apps/gmail/compliance
Select configure in the append footer section.
Add in any message you wish here or add in an image and it will appear at the bottom of all emails for gmail accounts within your organisation.
Be sure to check the tickbox for Append the Footer to messages being sent within your organisation if you want to get the message to appear when you send emails to your team otherwise leave it unticked and press Save.