(Instructions are for version 1.9.5 and above).
First Go To Connect Apps & Services and choose 'Connect To TrainAsONE'
Then Connect. As you will see stated you can now access your training plans in Training Section.
Go Back To To The Training Section and choose the now visible 'Access TrainAsONE Plans' button. (If it doesn't appear, try navigating to another tab and back again as It can take a few seconds before it becomes available after connection).