AddEntityCollideCallback("Player", "ScriptArea_2", "Func01", true, 1);
This should be in the braces of OnStart, not a standalone {}.
Keep in mind that { is used to open a function block, and } is used to close it. Every function block should have a name or an indicator. So it would be like this:
////////////////////////////
 // Run when entering map
 void OnEnter()
 {
 }
 void OnStart()
 {
 AddEntityCollideCallback("Player" , "ScriptArea_1" , "MonsterFunc1" , true , 1);
 AddEntityCollideCallback("Player", "ScriptArea_2", "Func01", true, 1);
 }
 void MonsterFunc1(string &in asParent , string &in asChild , int alState)
 {
 SetEntityActive("servant_grunt_1" , true);
 }
 void Func01(string &in asParent, string &in asChild, int alState)
 {
 AddPropImpulse("ScaryDoor", 0, 0, 5, "World");
 PlaySoundAtEntity("", "21_bang_door.snt", "ScaryDoor", 0, false);
 StartPlayerLookAt("ScaryDoor", 2, 2, "");
 AddTimer("", 2, "TimerFunc");
 }
 void TimerFunc(string &in asTimer)
 {
 StopPlayerLookAt();
 PlaySoundAtEntity("", "react_breath_slow.snt", "Player", 0, false);
 }
 ////////////////////////////
 // Run when leaving map
 void OnLeave()
 {
 }
 
If you don't have the sound files notes will skip instantly.