Anyone who knows how to enable the long sleeve
jerseys for all the teams, please help me.

Well, I haven't tried this and I don't know if it works, but has anyone tried to change the file name of a goalie jersey (gk001.fsh) to pk001.fsh? THe goal keepers are the only ones with long sleeves?
Just an idea

That's been tried, I think it's an option for long sleeves. Let's wait for FEd and see...