I was told by SweetieJean that I'd need to pay for and download TT Business for my C Corp. Upon doing so, the system stated that I "already enrolled in TurboTax Advantage"... So, is there another download for the TT Business, which I already paid for?
TT Business is a different product than TT Home and Business, which you apparently already have. Go here:
Business is used for Form 1120-C for a C Corp.
Home and Business is used for Form 1040, Schedule C.