You've probably already found your answer, but others may have the same question.
The amp can run stand-alone, but it requires a 24VDC supply connected to the Crestnet terminal. The amp doesn't need to see Crestnet, just to have the 24VDC to activate its relays. Once that's done, all you have to do is put the power switch in the ON position, and push the Override button on the back. This will turn on the amp and all amp channels. You can now turn the amp on/off with the front power switch. The downside is that if you lose the 24VDC power, you will have to push the Override button again, so make sure it's accessible.