Perhaps this one would be better translated as "where did you meet in the last year", while the "tavaly" version would be "where did you meet last year"?
It might be that I'm just saying that both work in English also. (There is a subtle difference, but I'm struggling to explain it!)
In your example, both of your questions are possible, and have slightly different meanings.
However, at least in my dialect (and I think in standard English in general), "have you met last year" is not possible -- in general, perfect tense (e.g. "have met") + time (e.g. "last year") does not go together, since perfect tense is about experience (has this ever happened) and not about a specific point or region in time.
you (singular) met - (te) találkoztál
you (plural) met - (ti) találkoztatok
Both are correct for "you met". But, in this sentence the plural version is preferred, since you guys can meet each other, while you alone should meet someone else.... so the sentence would be better as "Hol találkoztál Katival?" - Where did you meet Kati? Or anyone else in place of Kati, but not just találkoztál alone.