How should I matching the impedance?

Impedance matching is a requirement for certain kinds of communications wiring, not 4-20mA loops. Whoever offered that advice is clueless. It is unfortunate that bad advice is mixed with good on the internet, even on this forum, but you get what you pay for. /:

However, while it's not an Ignition question, Ignition is pretty popular with engineers who understand such things. And some of us hang out on the forum. (:

All that aside, there is an existing topic from @velpandianp. It is inappropriate to repost. Further answers should be over there: