The desktop software and online versions are two different platforms and do not communicate for that purpose of automatically unlocking prior returns, but your purchase does still qualify.

So you'll need to phone TurboTax Customer Support during business hours.  Tell them of your desktop software purchase and ask them to unlock your online prior returns.

You can use the form at the link below to schedule a call back, or it may provide a number.  Hours are 5AM-9PM Pacific (8AM-12 Midnight Eastern) 7 days/week.

Where the form asks what product you are using, be sure in the dropdown menu to indicate "CD/download" and the proper operating system, then indicate which Edition.

https://support.turbotax.intuit.com/contact