Basically I went through a 3 hour chat session with their CS, and it turns out that they do not support countries that doesn't use a zip code, e.g. Hong Kong.
They are trying to blame it on Google's API, which works just fine on its own to find the geocode for any Hong Kong addresses.
The only "solution" I got form them is to use a plugin that charges $19.9/month for a basic function.
We decided to set up an online store as covid is seriously affecting our retail business. And now I have to pay extra dollars for this basic function. I already paid for 1 year of subscription of Shopify's plan, and none of the documentation online mentioned this huge flaw in the "local delivery" service.
No reimbursement/compensation is available, and no plans to fix this bug anytime soon (I've gone through every single thread on this issue, and seems like the problem's been around since 2018).