It sounds like it is probably a part of a bigger sentence. You could say something like "You will need to arrange everything in person." That would mean that you will need to make all the arrangements by contacting the relevant people directly, on the phone or face to face. If you have to do it "in person", you can't do it through an internet site, or through an travel agent, etc. You have to do it yourself, by direct contact.

in person = personally, witness own eyes

It's not something I've heard before. What sort of context would you use it?