That is because Upgrading is a two step process.
Adding a credit card on file (this is most likely already done)
Then choose a plan and clicking “Buy Now” and confirming the purchase (you will also be emailed a receipt)

Adding a credit card on file (this is most likely already done)
Then choose a plan and clicking “Buy Now” and confirming the purchase (you will also be emailed a receipt)

Updated on: 25 / 05 / 2021