According to the following page, members of the local admin group on the machine hosting Admin Hub can access the site:

https://doc.laserfiche.com/laserfiche.documentation/12/userguide/en-us/content/admin-ref-intro-adminhub.htm

Can users that are not members of the local admin group be granted access?

Currently, they are able to reach Admin Hub (e.g. https://<admin_hub_host_server>/AdminHub/Server) but cannot login.