What about Hong Kong and mainland China visas? Do they have the same requirements?

I am planning to go to mainland at first, but after realizing that my ARC validity is not more than 6 months the time I apply for it, I altered it to Hongkong because for Indonesian, we are allowed to travel free for 30 days.

The question is, if my ARC card is expired in Sept and I want to travel to HK in June. Is it okay? Bcs it will be a whole different story (which is a NO) if I was applying for Chinese entry permit for mainland.

Thankyou!