"Sorry, the payment amount is invalid."

Hi afraidofdark,
There’s an thread on forum to list out the current known issues with payment.

This is on us to fix. There are a lot of discussion internally, as well as with our payment provider (Chase) to see how we can resolve this.

I apologize for the payment issues that you are having.
I’ve sent an email to our billing team to reach out to you directly.

Thank you again for your interest in our engine and toolsets.