Pls help advice on shimano steps display upgrade

[Apples24]

So I have a sc-e5000

I’ve seen a sc-e5300

Googling it I can use adaptor EW-AD305


When I look at pic of adaptor it’s just a round short plug

So

Does it plug into my older wire on one end and the other end slot into my new display or do I need a cable too?

Nothing seems explanatory

Thankyou

Lee