The stock Mustang has a mostly automatic clutch adjustment. Pulling up on the pedal releases the quardant and allows the clutch to adjust. The effect of this is the TOB will be in contact with the fingers at all times. This is by design.
Because the TOB is normally in contact with the clutch fingers, the service life of the TOB is not super great. The other "artifact" of this system is the clutch free pedal travel is much less than other cars. This gives the impression that it's not adjusted correctly.
To adjust the Mustang's clutch, pull up on the clutch pedal and then push to the floor.
Incorrect clutch adjustment will make it difficult to get into gear. Likely the clutch cable is not adjusted tightly enough such that the clutch is NOT fully dis-engaging. This can cause difficult shifting.