The system requirements for Cycles 4D are:
Cinema 4D version
Cycles 4D will work in these Cinema 4D versions:
A 64-bit machine is required, but you need such a machine anyway for Cinema 4D R16 and later.
Cycles 4D can render on the CPU in any machine or on the GPU if you have a suitable graphics card. What then is a suitable card for rendering with Cycles 4D?
Most, though certainly not all, PCs use nVidia cards. Which card is "best" for rendering with Cycles 4D is not an easy question to answer, especially since it tends to vary as the graphics drivers and the CUDA SDK are updated.
As a general rule, when choosing a card for this purpose look at the card processing power, usually measured in gigaflops or teraflops (1000 gigaflops = 1 teraflop) and the amount of video memory (VRAM) on the card. The more of each the better, but if you have to compromise on one, choose the faster card rather than the one with more VRAM. The exception might be if you wanted to render huge scenes with many objects, as the render engine is limited by the amount of VRAM.
You can also look at various benchmarks which have been published for Cycles, which are easily found on the net.
At the time of writing (November 2016) the Titan X is probably the best performer but the cheaper 980Ti is almost as capable - but doesn't have as much VRAM. Cheaper cards than that which also perform well would include the 780Ti or the 970.
Those Macs which use nVidia cards also work perfectly well and you can render on the GPU without problems.
At this time it is not possible to make recommendations for AMD cards. If you are a Mac user you probably have an AMD card which you cannot upgrade or change for an nVidia card. Although Cycles 4D does support AMD cards through the use of OpenCL, complete support is not possible due to the current state of OpenCL drivers for OSX.
Unfortunately, on some Macs Cycles will crash if you try to use OpenCL to render. This is most likely to happen for cards which are unsupported, but ideally using OpenCL on such a card would not crash. There isn't very much we can do about this because it is due to the drivers used, not a bug in Cycles 4D. We suggest that before attempting OpenCL rendering for the first time on a Mac you save your work and simply try it to see what happens. If you do get a crash, you can of course still render on the CPU.
Not all AMD cards are supported by Cycles. GPU rendering is supported for cards which use the Graphics Core Next (GCN) architecture level 2 or higher (GCN2+). GCN1 cards are no longer supported.
The architecture for AMD cards is shown on this Wikipedia page, but note that you will need at least an Rx 200 series card (AMD calls this 'Sea Island'), Some Mac Pros have cards which were especially designed for Apple and which won't appear in this list (e.g. D300, D500 and D700 cards). These are versions of standard AMD cards and you can find more details here. Those cards use the GCN1 architecture so are not compatible with OpenCL rendering in Cycles 4D.
If you aren't sure what card you have in your machine you may find the website EveryMac.com to be helpful. This lists the hardware of almost every Mac ever made; simply click the icon for the type of Mac you have and scroll down the page which appears until you find the section dealing with graphics or video hardware.
If your AMD card is not supported you can. of course, still render on the CPU. If you have an older Mac Pro where you can upgrade the graphics card then there are options you can explore but it is not possible to recommend any particular card.
The minimum requirement is for 64-bit Windows 7 or a later version of Windows.
For Macs, OSX 10.11 El Capitan is the minimum recommended version to use with the Cycles engine, since it contains vital fixes from AMD for when rendering on the GPU (for AMD graphics processors, of course).
Cycles 4D must validate your licence after installation and once within every 5 days after that. Therefore to use it your machine MUST have access to the internet before you use it for the first time and sufficiently often after that to enable repeat validation. It does not require constant net access all the time.
Needless to say, internet access is required for the on-line updater to work, but you don't have to use the updater if you don't want to.