How can I get a VOA? Do I just arrive in Beijing?

Dear, if you go to Shenzhen, you can get a 5-day VOA there. if so, you don’t need an entry permit.
But if you go to Beijing, you cannot get it. Or if your layover time in Beijing is less than 72 hours, and after that, you fly to a third country or region rather than Canada, you can enjoy 72 hour free transit in Beijing. In this case, no entry permit is needed.