Gave a quick look at the FAQs, and myself an answer.

Sorry for the disturb.
M.

Hi Hellguy and Beppe,
I'm on a MacBook Pro 15-inch Late 2011 equipped with an i7 2.2GHz and an AMD Radeon HD 6750M 512 MB. Yosemite 10.10.2
Being the gpu a Radeon, I cannot make use of the Nvidia drivers and generally, I suppose, of the whole architecture around CUDA.

Is Octane a CUDA only renderer ...

No version downloaded would start, an error message shows up and then the software quits. Even the 2.21.1 for which I don't have a license being a student trying to use the student license.

"OctaneRender 2.21.1 cannot be opened because of a problem.
Check with the developer to make sure ...