connect PAG1 ( or PAG2 ) output to AUX or LINE input of amplifier.
You can adjust paging audio level in 2.System / 11. Audio gain / 1. Paging/MOH
PBX and audio devices must be connected via audio transformer (galvanic isolation).
and connected to an EPG port (every Panasonic PBX has this)
For this solution every Panasonic PBX has at least one port named EPG ( External pager)