Can't i provide business details on my antiques sales to complete a schedule c without upgrading my turbo tax subscription? i did in prior years.

If you are using TurboTax Online Free or Deluxe, you will need to upgrade to Premium in order to enter Schedule C. (TurboTax Free has different limitations this year.) See this FAQ for more information: How do I upgrade or switch to a higher version of TurboTax Online?