– DLC files were encrypted with a console-specific key, meaning they could only be used on the 3DS that downloaded them.
Let’s address the elephant in the room: No, you cannot magically unlock DLC for free on an unmodified console. To install archived DLC, your 3DS must be running custom firmware (CFW)—specifically Luma3DS. 3ds dlc archive
While Nintendo technically allows redownloading "previously purchased" content, many games (like Monster Hunter and Super Smash Bros. ) required an active online connection to fetch that data from within the game's menus. With online services now dead, even some legitimate owners are finding their paid content inaccessible. – DLC files were encrypted with a console-specific