International Priority Express Shipping

I’ve had international orders before but I just got my first one that paid for Priority Express, has anyone used an Etsy printed label for this shipping speed and did it work out ok? I only ask because my post office told me I should do domestic Priority express orders in-store because of the specific label it needs so I wonder if I’m taking a risk going through Etsy on international express or if they’ve just made me paranoid for no reason.