I've set up a Multi Tenant Organization, but I'm not sure if the user contact information is correct

Hi,
Thanks for the response, however I'm still having issues.
I think the first part is working, having done Set-CsTenantFederationConfiguration -SharedSipAddressSpace $true though I'm not quite sure how to test that.
But as for the second, I still don't have the "chat" link and your instructions don't quite match what I see.

1. Go to Microsoft Teams Admin Center → External Access
   ok
   
   
2. Ensure "Users can communicate with other Teams users" is enabled
   ???? I see no such option
   

    

3. If both tenants allow external access but still have issues, try adding each other's domains manually:
   • Click "Add a domain"
     
     Where??
     
     
   • Enter the other tenant’s domain (tenant2.onmicrosoft.com)
   • Set it to "Allowed"
4. Restart Teams and Outlook.

Also, I check Global Address Book policies, neither tenant has one currently.

As for 
Ensure Both Tenants Have "People Search" Enabled
Do you mean "People Insights"?

regards
Lefty