I am unable to link to Schedule C or Schedule F on Form 1099-G. It gives me instructions to selected "Federal" from a list, but the highlighted box is a text input.

A 1099-G for your state tax refund should not be linked to Schedule C or Schedule F.  You should select Federal from the highlighted list.

There is no highlighted list for me to select from. It's an empty text box next to "Schedule C line 6" that is highlighted. I am on the "Check This Entry" page.