The start byte is 0x80. That is 10000000 in binary. Since none of the data that follows ever has the high bit set, a byte that does have the high bit set defines the start of the command sequence.
The command to change the configuration is 0x02. Why you insist on switching bases is a mystery, but, in this case it doesn't matter.
The third byte defines what the new configuration is to be. The 6th bit of the byte defines the number of motors. You are sending 2 (= 0x02 = 00000010). The 6th bit is 0, which means that you are setting it up to control 2 motors. The remaining 6 bytes define the motor number. The directions regarding the motor number don't make sense to me. If appears that the configuration step applies to 2 motors, in two motor mode, not to a single motor. It also appears as though the numbering convention would allow you to control 32 motors. The driver is not capable of that, so why the protocol supports it is a mystery.
Since the configuration command is always three bytes, it is unclear why you are sending 4 bytes, or what you expect the 4th byte to do.
Are you resetting the controller after sending the config command? Does the appropriate LED blink on the controller?
Why are you sending the config command in loop()?
How is the controller connected to the Arduino? A high res picture is needed.