When do we use "at" and "in" with "arrive" talking about place, not time?
Arrive carries 3 prepositions: in, on, or at.
So it turns out that 'arrive' either carries or doesn't carry a preposition depending on the place or time that follows it, i.e. if the place or the time carries a preposition.
'at' with a specific point in time = "I will arrive at 4:30"
'in' with a period of time = "I will arrive in 30mins"
Confusingly it's 'on' with a day = "I will arrive on tuesday"
'in' with general areas, countries, cities etc. = "I will arrive in Italy", "I will arrive in Rome"
'at' with specific places = "I will arrive at your house", "I will arrive at the airport"
You can use also use 'in' with a specific place if you mean specifically inside.