Are your users receiving “Error: Access Denied” when accessing the SharePoint Online Team Site?
Here is how to resolve it…
Log into the Office 365 portal as the global admin.
Access the Team Site
Click the Site Actions drop down (top left corner of the page) and select Site Settings
Under the Users and Permissions click on People and Groups
Click the New drop down and select Add Users
In the Select Users section, enter the name of a user that has been assigned a SharePoint Online license and click the Check Name icon.
Once the name is validated, click OK. NOTE: If the name does not validate, it is potentially because the account has not been assigned a SharePoint Online license.
The new user appears in the Team Site Members page. At this point, the user will now be able to access the Team Site.