“Virtual disks that dynamically expand aren’t supported by Exchange” – This is true but “not supported” and “don’t work” are two different things. The dynamic disks aren’t the cause of your problem simply due to the fact that they’re dynamic disks.
Exchange related services did not start. I rebooted the machine three times. I was guessing it was a low RAM, but then I read that and, unlike joeqwerty, I thought that “not supported” actually meant “it won’t work.”
The firewalls in both the DC and the Exchange machine were ON.
So now I am installing it on a 50 GB fixed Virtual Hard Drive.
IMHO RAM is the issue – even for a training environment, about 8Gb is needed
Speed of drives may also be an issue – my training laptops can run 2-3 Exchange 2013 servers, plus a DC and client on 16Gb with an SSD, but without an SSD I see the same behaviour as you