I signed up for my first race using Zwift Companion - selected cat D as I am a beginner AND an old fart…but the only start line I could access, despite several attempts to End Ride and sign back up…was a Cat A race.
NOT a nice first experience…as it was a time trial for 95% of the time and I was last of the finishers.
Any ideas?
Firstly welcome into the wonderful world of zwift racing , it can be challenging to learn all the key steps to get most out of it , because it has largely been developed by the commnity so many things you need involve using tools and solutions outside of zwift itself.
Have you linked your account ro zwift power so you can better see your expected category and find a more engaged way to find appropriate and popular race events that would suit what you wanted . ( there are other systems that also offer value add on the later but start point would be zwiftpower)
Welcome to the forum.
The easiest way to sign up for a event is by using the companion app.
I’ve done a stack of rides on Zwift - I also use Sufferfest and others - I know my numbers. “I know my place”. When I have entered events using Zwift Companion before, there’s been no problem - I enter as D and ride the D events. This time I did the same, entered as D, but Zwift stuck me in an A race and I could not get out 
Zwift “knows” my power numbers OK - if I do a structured workout it is paced appropriately, so I guess this may have just been an isolated glitch. But I really don’t want to ride a cat A race again - although it was exciting to be plodding along at 1.8-2w/kg and have an attacker go past me at 13w/kg +, folowed bya flat-out chasing group (on their last lap)!
Can I ask what event was it ?
Some events have specific rules and settings such as All riders being visible for example so you would see all the A riders .
EVR Definitely Not the WTNC.
As I said, I entered using Zwift Companion and there was a clear choice of categories.
However, looking at the results, there don’t seem to be ANY Cat D riders, so maybe that’s the explanation.
And yes, during the ride all riders were visible - I saw other cats in the “nearby” list.
I’m on Zwift Power now - thanks for the suggestion.
The easiest way to sign up to an event (and understanding what you sign up to) is by using Zwifthacks event search and then whatever signup option the signup link opens on your platform…