Explanation/Reference:
Explanation
A: Office 365 Groups are a shared workspace for email, conversations, files, and events where group members can collectively get stuff done.
You can use groups to collaborate with people across your company, even if they don't have access to Microsoft Dynamics CRM Online.
Before you can start using Office 365 Groups, the groups solution needs to be deployed and turned on for your CRM entities.
Provision Office 365 Groups
1. Browse to the Office 365 admin center and sign in using Office 365 Global administrator credentials.
2. Click Admin > CRM.
3. Click the Instances tab.
4. Choose your instance, and then click Solutions.
5. Select Office 365 Groups and then click Install.
6. Review the terms of service and then click Install.
You can configure OneNote in CRM Online when you're also using SharePoint Online. You must have a subscription to Office 365 to use OneNote in CRM Online.
E: Configure Office 365 Groups
Once you provision Office 365 Groups, you can enable them for any entity. Security group membership is associated with the entity. You configure Office 365 Groups in CRM Online.
1. In CRM Online, click Settings > Office 365 Groups.
2. On the Office 365 Groups Settings page, click Add properties button Add entity and choose an entity from the drop-down list. Repeat this step for each entity you want to enable, including custom entities.
Etc.
References: https://technet.microsoft.com/library/dn896591.aspx