We can't officially support Unity 5 at this point as it is still in beta, and we don't have access to it. Naturally we will aim to support it as soon as possible after release. We have also never tried a 64-bit version of Cubiquity with Unity and so it is unlikely to work without some modifications to the code.
That said, it doesn't hurt to try, so I can give you a 64-bit version on the off-chance that it does work. The build below should match the latest release on the asset store (1.1.3), which I assume is the version you are using. If you are using the version in our Git repo then let me know and I can build a 64-bit version for that.
Download: https://drive.google.com/uc?export=download&id=0B7b4UnjhhIiEUzVJM3RYZ0ZlcWcYou can probably place these in the 'Assets\StreamingAssets\Cubiquity\SDK' folder, replacing the ones which are already there (back them up first). The .dll should then be automatically copied to the root of the project when you run Unity.
Have you already worked with Cubiquity with Unity 4? It will be useful if you understand which issues are specific to Unity 5. In particular, I know that the shader system has been overhauled for Unity 5 so you can expect some issues there.
Edit: I should have said those are for Windows. OS X will be more difficult but I can give it a try if need be (probably not until the weekend).