Robin Hi 👋🏼 Robin,
Yes, you both have to have a bunq account. But, that doesn't have to be payed account, you could even both have a Free account. But it all depends on what you are looking exactly. Several options:
One Premium - One Free
The premium user can create a separate bank account (one or more). This can even be a joint account. The premium user can share this account. And Premium users have access to cards and all features. A Premium use can share one of his cards with the Free user. But lending out card 💳 needs special permission of bunq.
Two Premiums
In that case you both have full access to every cool feature. With this combination every user will have his own set of cards.
Two Free's
In this option you both will not have any cards or access to cool features. And if you use this option, you have only 1 account each and no option to create a joint account. Not very practical since you both won't have any cards.
If you have any questions ❓ please shoot.
PS: you cold also take a look at bunq 🌈 Pack... that way a Premium membership will only cost €5