If you sold Rental Property in an Installment Sale, enter the sale in the Rental Section under Property Profile and Assets/Depreciation.
TurboTax will guide you to reporting the Installment Sale.
If you sold property that was not used for business in an installment sale, search for 'installment sales' and 'Jump to installment sales'.
Here's more info:
https://ttlc.intuit.com/replies/7144846