Ok so ive had to drag and drop some files to get classicube to even WORK and now its giving me another error when trying to sign idk if this is beacuase the newest 3ds build isnt finished or its something i did wrong this is on a old 3ds is says error B5510036 when signing in

Does the 3ds have custom firmware?

I also have an old 3ds and it doesn't have custom firmware

What is the system date and time set to on the 3DS?

(the system time being incorrect is one of the two most likely reasons you would receive this error code)