Aximmetry is node based so you can connect anything to absolute everything. In this case, just connect the billboard output pin from the camera compound to an output. The easiest option is to just drag it all the way to the right where you already have connected your camera compound output. If you drop it below any already created outputs a new output will be created. This output has an output index, so just select that in the monitor index menu on your monitor puts, or map it in the settings.