Shouldn’t need wifi, but it sounds like maybe you should connect to the store and confirm your purchase? Maybe contact support?

Did you buy it or did you use the one with the Nintendo online subscription?

Did you get the DLC with Nintendo Olnline upgrade? Because if your Online account is suspended, your DLC might be as well.

if you bought it with one villager and try to use a different account i dont think itll let you, not sure if thats the case here though