Microsoft 365 Family Subscription - Activation Issue

Hello

Advice needed please.

My wife has purchased a Microsoft 365 family subscription. She has emailed an invite to my Gmail account (apparently that is all correct). 

When I go through the steps to join, using my Hotmail address, I eventually end up at this screen. So, I am not able to activate my invite.

I am on a brand new Apple Macbook Pro, so I know the issue is not the OS being out of date.

I have also seen this update on the URL below, but not sure if that is the current blocker: 

https://support.microsoft.com/en-gb/home/contact?SourceApp=smc2&ContactUsExperienceEntryPointAssetId=login.live.com

Any advice would really be appreciated.

Thanks in advance

Ben