TO CONNECT A Raymarine Magnum 4 Array TO MY AXIOM 7 DO I NEED TO BUY ANYTHING ELSE

You would need the gearbox p/n E70484 and cable.  The whole thing is sold as a kit, here is the link to it - https://www.boemarine.com/raymarine-4kw-magnum-w-4-array-15m-raynet-radar-cable.html