I just downloaded and attempted to install the open source version of m2 on Ubuntu. I had already installed M1 and that went pretty smoothly.
Unfortunately, it seems that the M2 source download does not include any of the servers. A quick comparison of the M1 and M2 downloads shows that indeed M1 is 150MB while M2 is 26MB. Consequently, installation is very tedious and time-consuming. In fact, I just gave up after spending more time than I had trying to find the right versions of the various servers required.
Were the servers left out of the m2 source download intentionally or is this a build error? I appreciate the work you've done with Zimbra, but I'm hoping that the installation can get a bit easier.