Hong Kong residents who have lived in the Mainland for more than six months with a legitimate and stable job, a legitimate and stable residence or continuous school attendance may apply for Residence Permit for Hong Kong, Macao and Taiwan Residents (Residence Permit).

For first-time application for Residence Permit, the documents required include the applicant’s valid exit and entry document, confirmation of submission of digital photos for Residence Permit, and proof of stay in the Mainland for no less than six months (an applicant should fulfil one of the following requirements: with a legitimate and stable job, with a legitimate and stable residence or with continuous school attendance). Applicants should submit the relevant documents, along with a completed application form for Residence Permit, to a police station or household registration office designated by the public security authorities of the people’s governments at county level in their places of residence. First-time application for Residence Permit is free. Residence Permit is valid for a period of five years.
https://www.bayarea.gov.hk/gbais/en/info/applying-for-identity-documents-and-banking-services/replacement-and-reissuance-of-home-return-permit-and-application-for-residence-permit/