Instacard have released a public dataset[1] on their orders, so it should be even easier to verify this claim. From what I could find in some analysis[2] of this dataset around 100k orders per day and not per minute seems accurate.
I assume they are referring to how many database requests they have due to customers orders or a similar metric and just worded it poorly.
That's fair as the Kaggle dataset[1] is from 2017. Even assuming orders scaled with revenue (which grew to $1.5B in 2020[2]), you'd only reach a few hundred orders/minute at the pandemic peak (which lines up with the calculation above via a different method).
So I still assume the original comment isn't referring to actual orders placed.