It seems the pay was for work you performed as an independent contractor in the past. Having said that, if it was a one-time occurrence or sporadic (like a hobby) you can enter without a Schedule C using the steps below.
However, if you develop apps even as a side job to make money then it is a business and you would enter the form as self-employment to generate the Schedule C. You would also be able to enter any expenses to offset income.
If this was not a business start by deleting the 1099-NEC and any business entries associated with that form to get a fresh start.
Then,
- "Wages and Income"
- "Other Common Income"
- "1099-NEC"
- Enter the form information
- "App Development" as a description
- Select "This is not money earned as an employee or self-employed....it is sporadic..."
The income will be reported as other income on Schedule 1, line 8z.