DL is using the common English translation rather than the literal one. "Puka" can be a door or a hole. It also means to emerge. "Puka Kula" literally is emergence from school. The common translation is graduation. "Ma'o" means "over there." So, "E puka i waho ma 'o" would be "Emerge to the outside over there."
(ʻŌ) used in pointing out a place when the person you are talking to does not know what place you are talking about. Usually ʻō is used with a pointing gesture.
Also: look at segment [3:28] to [4:40] on the link provided. Ka Leo ʻŌiwi | Episode 8: https://youtu.be/XzDZpCDJTn8
ʻaneʻi = here
ʻō = there (away from the person you are talking to)
laila = there (close / next to the person you are talking to)
The segment link above shows visual examples. (Start at 3:28 into the video.)
Iʻm trying to figure this out. E puka sort of means use the door; i waho means to/toward outside, and ma ʻō is there? So, because the door leads to the outside, itʻs understood to be the Exit?