When I try to install my Lightroom 6, I'm getting a message stating "OS requirement not met. Current OS 10.7.5. Mac OS 10.8.0 or above required" I'm not sure what "OS" is, or how to increase it..?
OS means your operating system. Lightroom 6 requires Mac 10.8 or above to run. You need to upgrade your OS as your machine does not meet the system requirements for installing Lightroom 6. System requirements
For best assistance, would ask you to contact Apple and check with them, if your machine is up-gradable to the latest version of Mac.