After I enable sync on my devices, the books I have in the Library of one device did not appear in the Library of the other devices.

The sync functionality implemented in Bluefire Reader syncs the last read page of the same book across devices that are authorized to the same Adobe ID. Currently the sync functionality does not include syncing copies of the same book across devices.

To learn about importing your library onto multiple devices, please navigate to the topic associated to your device's OS.