Orders from London?

Members of the resistance would go to London and give info on what the Germans were doing behind enemy lines and London would give certain orders to the resistance.

Check out the movie Army Of Shadows (1969), one of the best films on the French resistance. There is a part of that film where they sneak out of France to board a British sub to get to London, then have to parachute back into France off of a British plane.

Et in terra pax

As chief of the resistence, general De Gaulle was exiled in London, from where he organized the activities in French territory; hence the "orders from London".

Many resistance groups were in contact with England and supporters elsewhere outside the country - by radio and or/morse transmitters- ownership of which was punishable by death. The BBC in London broadcast coded messages to Free French and other Resistance cells all over France alerting when to expect bombings,arrival of vital supplies or personnel by sub., parachute etc. (see this:
https://www.theguardian.com/world/2014/may/03/d-day-bbc-occupied-france-letters )
And of course De Gaulle and his supporters had decamped to England to (help) direct operations, and to broadcast morale-boosting messages in French.