I did install BESx 5.0.3 together with Zimbra 7.1.3_GA_3346 and ZimbraConnectorBES_126.96.36.199.
I followed the instructions in the ZimbraBESConnector AdminGuide carefully and installed everything without any major issues.
I can now log in as BESx administrator (besadmin) and add ZCS users. But the users are not able to login (The username, password, or domain is not correct. Please correct the entry.).
I also checked and modified the Active Directory authentication settings in BES as described here. Still no difference...
The only thing I can imagine right now is that I also use AD authentication on Zimbra itself (External Authentication).
Any ideas where to start???