How to double-side print?

For the upcoming midterm, im allowed a double-sided, single paper for a cheat sheet. I went to the library to print on 2 different occasions to print double-sided and in the print.torontomu.ca, the setting is labelled duplex. Second time around, I made sure to check the signs on the printer that may state that its double-sided specifically, but it doesnt say anything.

Please help me, I can't really change the settings of the printer. Today I was in a rush to get to my midterm (different one) so I couldn't ask for help.

If I don't manage to print double-sided, might just tape the sides together or let the prof. know beforehand.