Just saw my android friend can download Douyin in their phone and i wonder is there anyway to download Douyin in my app store?

Just switch your region to mainland China will do
Google for detail steps

Switch your region and then download it.

Still cannot, any guide how to do it?

create apple id for china country.
there is a guide using itunes pc register apple id without china phone number. Try google it. Address, u can google any place in china just copy it.

after that, u will be able to use that china apple id to download anything from china app store including douyin and wang zhe.

But how do we register an account for douyin? Use malaysia phone number or apple id or wechat all cannot.