The message says "Could not start purchase"

The message says Could not start purchase It adds: Check your connection and signed-in account, then try again.

The purchase did not start, so nothing was charged.

1. Check that your phone is online.
2. Check that you are signed in to your SkipTube account. Pro stays with it.
3. Tap Get Pro again.

If Apple's payment screen opened and took the payment, but Pro is not on, see Finish the activation of Pro.