Is this what you didn't understand: If there is a payment owed with the return, which is on extension, you should already have scheduled and made the payment when the extension was filed for. Filing the actual return now means the payment is already late. You are being asked to schedule the payment that is already past due. It isn't due in Oct. Only the form(s) have the Oct due date.
"Level Up" is a gaming function, not a real life function.
The payment was due back on July 15th, so since its late, it will only let you choose the current date for direct debit.
If they don't want to pay now but you want to Efile and get it off your desk, they can make payment when they're ready at IRS Direct Pay, or give them a payment voucher to mail a check.