I think it is best you contact Scirra directly. Russian colleagues of mine (working here in Europe) cannot send any money to their families in Russia because of those sanctions. Some of them, make money transfer over China but I have no idea how they do it. Your transaction will go in the other direction.
Despite the fact this is very unfair, we as citizens can't do anything about it.
Therefore, I think your best option is to contact Scirra and explain your problem. It is very regretfully, that those innocent people also get affected by those sanctions.
Hope you can solve your problem and buy your license.
Chris