There are two options:
The Library can be manually shared with the subscriber. The Library owner can click the share icon and send a link to install the Library by any of the usual methods. The subscriber then has a read-only copy of the library on their dashboard.
- The Library can be published to the subscriber. The library owner can add the library to an unlocked or locked tab and it will be be published to the analyst and reader users as long as Push Publishing is enabled.