When getting to the final stage to file, I'm hit with the prompt to upgrade to TurboTax Deluxe due to an additional Medicare Tax Form. But I don't have this form?

This form is added when the Medicare wages on your return exceeds certain thresholds that trigger the tax.  For married taxpayers filing a joint return this is $250,000.  For single, head of 

household, and qualifying surviving spouse it is $200,00, and for married taxpayers filing separate returns it is $125,000.  

For more on this topic see IRS Topic no. 560.