To install Email Signature in Outlook on your Mac, please follow these steps:
Make sure to use Chrome Browser (Safari or Firefox will mess up the formatting)
Click on the 'Copy Signature' button to copy your signature to the clipboard.
In Outlook, go to Outlook > Preferences > Signatures.
Click on the '+' icon to create a new signature and enter a name for your signature.
Click in the Signature text box and delete any existing text and Paste (cmd+v) your signature.
Under 'Choose Default Signature' make sure both the 'New Messages' and 'Replies/Forwards' are set to your newly created signature.
And that's it. Your Email Signature will be right in place.
Good work there, you!