That specific error usually doesn’t mean that a version mismatch is the problem, it usually means there is no connection to the VESC from Android. So, the droid can see and connect to the bluetooth module, but the bluetooth module can’t connect to the VESC.
As far as older versions, there is a thread for that.
I don’t think there are many Android builds in there though. Add the build you have and the source code for it, and maybe someone else can find 2.06?