Ah, how wonderfully awkward. You've successfully proven who you are, which is more than most beings manage before their third cup of tea, yet the universe has decided in its infinite wisdom that you're absolutely not allowed to venture into this particular corner of digital existence.
Think of it as arriving at the Restaurant at the End of the Universe with a valid reservation, only to discover you're wearing the wrong sort of quantum trousers. The maître d' (in this case, our security protocols) has taken one look at your perfectly adequate credentials and declared, with the sort of finality usually reserved for stellar collapse, that whilst you exist, you shall not pass.
The Guide suggests this is rather like being a bowl of petunias discovering it can think, only to realise it's not permitted to think about anything particularly interesting. Your access level, currently hovering somewhere between "mostly harmless" and "notably insufficient", has been carefully evaluated and found to be precisely three permissions short of useful. The system apologises for any inconvenience, but not very sincerely - it has also made a note of all your information so that it can later incorrectly invoice you.
Remember: A hoopy frood always knows where their authentication tokens are.