Not to be a party pooper, but i'm pretty sure carry in this situation means "hold in your hands for the granted armor class". At least that seems RAI.
RAW... I may be wrong, but I actually think D&D doesnt actually have the phrase "equipped", so carry would still mean exactly that, carry in your hands, not keep it around in your backpack.
I just checked PHB 142-143, Move Actions: Ready or Loose a Shield.
"Readying" a shield refers to arranging it in a way that it provides an AC bonus. "Loosing" is the inverse. But the last sentence is the fun one:
"Dropping a carried (but not worn) shield is a free action."
From that, it looks like "carry", in this context, refers specifically to holding a shield in one's hand without employing it to gain an AC bonus. (To get the AC bonus, you have to
wear the shield, which is presumably the state of affairs after
readying it.)
Hilariously enough, a version of this plan might work by RAW. So, you Druid players, be careful when you're looting your fallen enemies, and don't pick up any metal shields!