Yes, you need a CMC amplifier or some other active arrangement such as a KC cable and an nBox. But in professional applications an actual CMC amplifier is nearly always used because it puts out a balanced, low-impedance signal right behind the capsule. That gives you the best arrangement by far in terms of RFI and hum/buzz rejection. In fact, until reading this thread, I had never heard of any professional film or video sound recordist NOT using a CMC amplifier for a Colette capsule.
Of the available amplifiers, the CMC 1 is the one that I'd recommend. It has better rejection of RFI, lower current consumption, and (at 48 Volts) 4 dB better headroom than either the CMC 5 or 6. There are three different models depending on the cable configuration that makes the most sense for you. Please see
https://schoeps.de/en/products/colette/microphone-amplifiers.html .
The CMC 5 amplifier isn't an option any more unless you buy one on the used market. But the CMC 6 is definitely preferable to it, again in terms of RFI rejection and also the capability of running either at 12 Volts or 48 Volts; for battery operation, 12-Volt phantom powering is twice as power-efficient with that model. And the CMC 1 is again preferable to the CMC 6 in terms of even better RFI rejection, lower current consumption, and of course the size and weight advantages.