What version do you have? If it is v3, it is that you can only enter your Gamejolt account, but the page where this version of the game was kept has already been removed, so entering is no longer valid.
And to play you only have to select one of the files, make sure you do not have a save file somewhere in the folder, This version of the game is very old and the save does not work.
the latest version of the game is on Gamejolt:
https://gamejolt.com/games/SMBLostland/386881
this if the save works but still has several bugs to resolve. :D