So, you did not do adequate research beforehand on the Great Firewall. Billions of people manage without Google services because better alternatives exist. Would it surprise you that Meta products also do not work there ? Try Microsoft next time.

There is a thread on proper VPN technique but that should have been sorted out before arrival. Your best hope is to use your foreign SIM and retrieve your Google items that way.

As for the Alipay 支付宝 payment issues, it's hard to diagnose. Did you do the whole identity vérification beforehand ? Every bank is a bit different, sometimes they can be the ones blocking the transactions. When I set my 微信 and 支付宝 payment services up years ago, I did not have to provide bank statements, but passport, selfie, ID etc.... were part of the vérification process.