Does the auxiliary police recruited by Zhangpu County belong to the security company?

Don't belong. The security company is a public institution. Auxiliary police are temporary employees of government agencies and institutions, so they are neither administrative nor institutional. Most of them are contract systems. The public security organ that accepts the security service company shall conduct an audit within 05 days from the date of receiving the application materials, and report the audit opinions to the public security organ of the local people's government of the province, autonomous region or municipality directly under the Central Government.