Unfortunately the Nvidia 500 series did have a number of problems running iClone 6. That is not to say that it won't work but we did see a number of Nvidia 500 users who reported issues.
However, iClone 6, unlike iClone 7, does allow you to run in DirectX 9 mode instead of DirectX 11 mode so you may be able to get iClone 6 running that way if you do have problems.
Really the best to try it and see if it runs. If you have the 560 or 580 model then performance may not be too bad but any lower and iClone will likely struggle with anything more than very basic scenes.