we'd need more of your code to clearly identify your issue, but there already several things which are going wrong here.
So,, if I tell bgt, at 6 seconds to play a sound, it will. However if I assign an integer value to 6000 and tell it to do the same thing, btt refuses to listen to it. Why is this?
I don't know what clock actually is. Is it the result of a timer, so e.g. some_timer.elapsed? In that case, you should always check for a greater result as well, because it is very unlikely that someone or the program executes that command exactly at 6000 ms, its more likely to be executed somewhat above 6000. So, if(clock >= 6000) would be the correct condition here.
that works, but this doesn't
We'd need more information about intvar. Which data type does it have? Did you initialize it with some value or is it just declared and thus 0?
Also one more question, why does it not play the sound if I am actively pressing keys? If I want even the standard number to work I can't be pressing other keys or else the sound will not be played. Has anyone else experienced or solved these 2 issues?
It is deffinitely your code to blame here, but since you didn't show that part to us, i'm unable to tell you anything. It is possible though and several games do that already, so more info could help to solve your problem.