internal server error fix?

i've been trying to start a lucky block server for the past few hours.

every time i join it gives me this message "Internal Server error"

i also can't find my playerdata folder

[17:33:28] [main/ERROR] [FML]: FML appears to be missing any signature data. This is not a good thing

i dont think this is supposed to happen

edit: i also found my playerdata folder, sorry for being so stupid

https://mclo.gs/LmWk1lq

i honestly think its a mod but im not too sure