dlc did not install

[KSJ_papermario]

simply put i downloaded the splatoon 3 dlc nsp and i installed it and it said succsful but when i tried to go to the dlc it told me to update and restart

 

[thesjaakspoiler]

Sometimes dlc content triggers a game update in order for the DLC to work.
You did install the base game?

My experience is that sometimes DLCs are bad dumps that don't work.
Changing the source sometimes fixes it.
Also note that some games have multiple regions (US/JP/EU) and you need the DLC for that region.
So a JP DLC won't work with a US base game.