Switch games require a specific firmware version (e.g., FW 15.0.1 or higher). If your CFW (Atmosphere) is on an older version, the NSP won’t install. A "patched" NSP has been recrypted to work on lower firmwares (e.g., backported to FW 14.1.2). This is rare for Final Bar Line , as most update groups simply require you to update your CFW.
If you have a modded Switch (Atmosphere + Hekate) and legally own the base game, or you are backing up your own copy, here is the step-by-step to assemble the ultimate Final Bar Line .