Good day, stefanoblack,
The free one-year subscription from TurboTax is exclusive to QuickBooks Self-Employed. It's complimentary from filing through TurboTax. Converting it to QuickBooks Online is unavailable.
You can export your data to TurboTax directly if you have QBSE.
For you to be able to get your free QBSE account, follow these steps:
Here's an article for future reference: QuickBooks Self-Employed Overview.
Let me know if you have more questions about QBSE.