In the subsequent issue of CUAmiga, they published a 'phone number for anyone to get the required serial numbers. I say numbers because there was also one required for the Magic Link software which accompanied the C4D programme.
The serial numbers were quoted quite freely, without them (Maxon, or their agent) requiring any proof of purchase of CUA, etc. While this service lasted, literally anybody could call and get the codes. I had the impression they (Maxon, or their agent) were simply fed up with the endless calls and would be glad to see the back of it.
In any event, CUA's C4D installer was flawed and many people couldn't get the programme to run, even if they had the codes. Shortly thereafter, however, CUA was history and all subsequent discussion took place through Amiga Format.
Whether AF actually discussed the codes I can't recall. I know some people regarded any subsequent publication of the numbers to be wrong, tho' I personally don't see a valid argument in that. Maxon (or their agent) were only too pleased to get CUA readers (and anyone else for that matter) off their back by releasing the numbers willy-nilly.
Anyway, AF did publish a solution via a CoverDisk. Presumably AF were fully aware of the CUA/C4D situation and duly decided there was no harm to Maxon (or their agent) in assisting CUA purchasers in getting it working. So, if you root around in AFCD35, all your questions are answered.
Cheers,
JaX