It says “Your age does not meet the requirements, so you cannot purchase additional content.” I understand that it’s saying I can’t buy it because of my age, but is there any way to get around this? Or do I just need to wait until I’m old enough to buy it?
It's because of the date you put in your Nintendo Switch account. You set your account age to be under 18 years old, which is too young for Pokemon Quest Microtransactions. It can be fixed by changing your birthday on the Nintendo website, as quoted by Gekky
Change your birthday on your account on Nintendo's website, not the switch commented 1 hour ago by Gekky
I may be wrong, but if I am be sure to tell me my mistake via comment.