Copy the oolib folder with contents into your KSP installation's Ships/Script folder. If it already exists, replace it. Carefully.
The files in the boot folder may be copied to your existing boot folder. Their names, especially boot.ks might conflict with existing boot scripts. In that case, resolve the naming conflict by changing the filename(s) to be unique.
This document is part of the kOS Object-Oriented Library documentation.
Copyright © 2020 Steve Meacham and contributors
Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License v1.3 or (at your option) later published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included.