I can connect ZS with Mac OS Lion and/or Ubuntu.
That work fine…
It’s possible you confuse the CA’s certificate.
Use the ZS menu :
X.509 CA / TrustedCAs
In the window select the certificate (probably : “Zeroshell Example CA…”)
Select the format DER
Click on the button Export.
The name’s proposed file is TrustedCA.der. Use this one for the WiFi setup.
(I know, it is late… latter is better than never 🙄 )