To Connect to Dynamics CRM 2011 Online with Data Synchronisation Studio you will need the URL to your CRM Environment.
For example one test environment of ours is at
https://simegoltd.crm4.dynamics.com for data sync you need to remove the Organisation name part so this becomes
This environment is pre-Office 365 Integration therefore if you have CRM Linked to your Office 365 Environment on one of the E plans then the Url will most likely be
You then Enter this into the CrmServerUrl property of the Provider, For CRM Online with LiveId choose the LiveId Authentication Provider, for Office 365 Choose Federated.
Next Enter your credentials under Authentication and then Choose your Organisation name from the Drop-down this might take a little while as it discovers the Organisations that are linked to your account.
Next Choose an Entity to work with from the Entity Drop-down.
Then Click OK to connect.
If you get an error message when you try to connect that the system cannot load the Microsoft.IdentityModel assembly then you need to install the Windows Identity Framework (WIF) then re-start Data Sync for the changes to take affect.