Translation:Please put up an umbrella.
It's accepted now. Additionally, while "put up" is not a particularly normal thing to say in English when referring to an umbrella, I think it gives a closer approximation of the Japanese: https://jisho.org/search/%E5%B7%AE%E3%81%99
差す: "(6) To hold up (an umbrella, etc.); to put up; to raise"
The answer it wanted does not make any sense in English. Put up an Umbrella? As a Native English speaker, I can say I have never heard that in my life. If it is about opening the umbrella to use it- we do not say "put up" because "put up" means "put away". If it is about putting away the umbrella, it has to be "the" umbrella. Anything else just doesn't make any sense.