Libraries are just paying for the ability to offer Libby to patrons.
Libby then taps into a login API for the ILS a library uses to check if a patron's library card and PIN are tied to an eligible account, and Libby offers its own content based on whatever each library can afford to offer.
You would need to offer your own content, ultimately, with the Libby model.
Same goes for OverDrive, Hoopla and Kanopy.
Libraries are just paying for the ability to offer Libby to patrons. Libby then taps into a login API for the ILS a library uses to check if a patron's library card and PIN are tied to an eligible account, and Libby offers its own content based on whatever each library can afford to offer.
You would need to offer your own content, ultimately, with the Libby model. Same goes for OverDrive, Hoopla and Kanopy.