noun, verbal noun, の adjective
You pour writing onto a form. You're filling out this form to order something new for yourself. It's a formal request to get this new thing (imagine it being something you're excited about ordering right now, and imagine yourself ordering it by pouring writing onto an order form).
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.
I don't really understand how to order at Starbucks.
You didn't forget to place an order, did you?
That’s an unreasonable request but we don’t have a choice.