I received a form N-288a from Hawaii so I entered it in Estimate Taxes but this puts it in the N-15 line 55 N-1 section rather than the N-288a section. What should I do?

Try the entry as shown below for this withholding so that it might flow to the correct spot.

The Hawaii (HI)  tax withholding (or federal ) can be entered in the following section of TurboTax so that it will flow to the HI state return.

While you are signed into your TurboTax account:

1. Federal Taxes
2. Deductions &  Credits
   
3. I'll choose what I work on
4. Estimates and Other Taxes Paid
5. Other Income Taxes
6. Scroll to Withholding not already entered on W2 or 1099 > Start
   
7. Enter the state withholding here (and/or federal)
8. Click the image attached to enlarge and view for assistance.

I had N288A withholding.  this works for the N15 Hawaii non resident