The "Allow customers to use discount codes when paying in installments" checkbox is disabled by default. Therefore, the discount code field will not be available when customers choose an installment payment option at checkout.
When the checkbox is enabled, a discount code field will appear at checkout for installment payments. Additionally, a new setting will be available in the app's admin panel: "Choose how the discount code will apply to the payment parts."
By default, the first option is selected — if a discount code is applied, it will only be used for the first payment. If the second option is selected, the discount code will be applied to all invoices.
