. Would you say "at" as in "The internet access at our booth (you're actually in the office and not in the booth when you're telling it) is hooked up."? -- Yes
And would you use "in" while you were in the booth, "We have internet access in this booth."? -- 'At' is probably a more common choice than 'in' here.
Would you say "The internet access in my room is not working."? -- 'In' if I'm in the lobby'; 'in' or 'at' if I am out of the hotel.
(When you're in a furnture store, yo say this to your co-worker) We need to buy a new fax machine. The one in our office is broken.-- 'In' or 'at': we are out of the office.
Years ago there was this question I failed from a tuturial class, and I don't understand why.
(In her girlfriend's apartment) Jame says: Look what I just brought! A computer. Her girlfriend, Macy says: A computer, don't you have one in your apartment.
The answer is: at. My teacher said "in" is impossible. No offence, but would my tea
Yes, your teacher was completely and utterly wrong. The use of 'in' or 'at' cannot be prescribed in the sentence and context you have presented. While 'at' is more expected, since the apartment is at a distance, no one can say that the speaker was not imagining the computer within the confines of the apartment walls.