I am currently a student at Hallmark institute of photography and we use Lightroom CS6 there. I also have a creative cloud membership on my Personal Macbook. Ive recently tried to open my CS6 catalog on my external hard drive through my Creative Cloud lightroom and It gives me an error saying the photos can't be found, I talked to my instructor and he told me that apparently Adobe doesn't allow you to work on two separate versions of Lightroom for one catalog? Is there a fix to this or is it set in stone?
There's no such thing as a "Lightroom CS6" and there's no such thing as a "CS6 catalog", exactly what do you mean?
Assuming you mean Lightroom 6 (without the CS), a catalog exported from LR6 can certainly be opened in Lightroom 2015 (the CC version); BUT the photo files to which that catalog refers, or copies of them, must also be on that computer (or a storage drive attached to it). Also, if they are not in a location that has the same path as the original photos' location in the school computer, the catalog will have to be amended to have the new path. A catalog is only an index of photo locations plus information about them - it does not contain the photo themselves.
An easier alternative is to export a set of Smart Previews together with the exported catalog and keeping them together in the same folder, transfer that to the Macbook. If the Smart Previews are available to the catalog, it will not need the originals.