Why am I being asked to check tax payments worksheet what does line 15 mean

Tax payments worksheet line 15 is for taxes withheld from form: 1099INT, DIV and OID.

To revisit that section:

1. Sign in to your TurboTax account and open or continue your return
2. Select Federal from the menu, then Wages & Income
3. Locate the section titled Investments & Savings and select Show More, then select Start or Revisit next to the form that you received. 

You need to check the box My form has info in more than box 1 to enter taxes withheld