A delivery window on a drop-off is optional. Shippers set one when the stop needs it, and the badge at the top of the stop card is where you see it: DELIVER BETWEEN two times, DELIVER AFTER one, or DELIVER BEFORE one.
When a drop-off has a window, the time that counts is the moment you tap Complete in the app, not the moment you park outside. A time-window incident opens when you complete the stop more than 15 minutes after the window closes, or before it opens. This adjusts the payment for that delivery job rather than your ratings. If you don't want to contest it, tap I do not dispute on the card and it closes with the effect applied.
If you do want to contest it, the incident arrives as a card in your Inbox, with a chat under it. Write what happened: the time you arrived, what held things up, and anything the shipper asked you to do while you were there. The shipper can take the incident off the delivery job.