Are you trying to play this on an or an emulator ? Do you already have Custom Firmware (CFW) installed?
If you don't have a 3DS, you can run these files on a PC using the Citra emulator (or its forks). 🛠️ How to Use a CIA File Download Crashmo | CIA File | 21M
Be cautious of sites claiming to host these files. Use a reliable ad-blocker and ensure your antivirus is active to avoid malware. Are you trying to play this on an or an emulator
Since March 2023, the 3DS eShop no longer allows new purchases. This has led many to "abandonware" sites for game preservation. Download Crashmo | CIA File | 21M