How to purchase Xbox Game Pass Ultimate?

When I attempted to purchase Xbox Game Pass Ultimate (with the $1.00 for one month sale) I was told that I needed a parent to buy this, and that a request could not be sent. (As is usually done for purchases requiring adult permission). It said I needed
to get permission another way, without specifying what “other way” I needed to do. So, I attempted to purchase it on a parent account. However, for some reason, it appears that the sale is only active on my account. On the parent account, it cost the normal
$14.99 for one month. How am I to purchase the subscription for my account (with the sale active,) without it saying I need to access an adult account’s permission “another way”?

:)