For versions released before 3.0.2073 the SharePoint connector defaulted to the legacy connection. However as Microsoft are deprecating the legacy authentication method we have shifted to use OAuth.
On-Prem SharePoint sites are not affected by these changes yet and the connector has not changed. You can find the details for connecting to SharePoint on-prem here.
With Data Sync you can Read and Write List Items and Documents in Document Libraries. We are still bound by the limits of SharePoint so if you plan on more than 5000 items in a list ensure you configure indexed columns.
If you plan to have more than 5000 items in your List(s) it is a good idea to plan ahead and configure SharePoint Index Columns. You should index any columns that you might use to filter the list for example if you plan to use incremental sync against the list ensure that the key column is indexed on the SharePoint List.
A quick video showing how to create a new Connection Library connection to a SharePoint site and then use the Connection Library to quickly connect to a List in the SharePoint Site.