Share Records with Groups

Share Records with Groups

how can i set up the crm to share records within the groups only? 
ie. users in group 1 can only see records in group 1?

I tried following < https://www.zoho.com/crm/help/security/create-groups.html#Share_Records_with_Groups> and tried to set up data sharing rules. 
However, I get an error saying I need to upgrade from Professional to Enterprise.

What am I doing wrong?