@EnHasSkill So there was a previous owner? That's good to know and yea, maybe the previous owner messed the tickets up, so my recommendation is still to search and eliminate tickets of other MK8 DLCs before installing the legit one.
With the informations that there was a previous owner and only a few games installed: Your last way out would be to factory reset the console. In case you have important save data use
https://github.com/Xpl0itU/savemii/releases/latest to back them up before / restore them after the reset. Note that this will disconnect all accounts through, so in case you're still using the account from the previous owner you might loose access to it, so also loose access to your eShop purchases! Also you will need to reformat your USB drive after that (that's why you should backup the saves even if the games are on USB). Also keep in mind that this is the most inversive method, so should really just be the last way to look at. Maybe others have ideas what else the problem could be (many pros don't look into GBATemp that often so maybe go to
https://discordapp.com/invite/F2PKpEj - this Discord is meaned for developers, not for questions from users, but I think your question is so delicate, it fits more to dev then user oriented).
