You only need to connect once and the skins are available until you turn off the game. That does not change the fact that, yes, the skins can be used in offline game modes. The previous answer to the question implied you could only use the skins in multiplayer, which is factually untrue.
Do you need to have an internet connection? Sure. Is that a big deal? Not really. Clearly the OP has internet, they should have no problems playing with their skins. Does it suck that you need to connect at least once per play session? Sure, but it's also understandable as that's how the servers verify ownership of the DLC.
OP is fine but that sucks for anyone else who buys this without knowing you have to have persistent internet connection and then is forever stuck with the default skins if they don't have PS Plus/XB Live. It's not too big a deal for my PC copy since my PC should always be connected, but this is pretty messed up tbh. It's a very big deal for those who are unaware.
Imagine paying nearly double for content you'll never have access to on your account because you don't pay for online multiplayer. Smh.
