I have a 5 man roster which doesn't include a bench player due to salary cap. But, I have been noticing the fact that I can't score any fantasy points anymore. I have 200,000 left so I traded Jimmy Butler for injured Kawhi Leonard. Kawhi is cheaper so I can get a bench player but I'm out of trades after the Jimmy Butler trade. So, just asking, does a team need 6 players in order to earn fantasy points.

Please answer ASAP

can I have an extra trade because of this, its really unfair and I'm competing with people, and I'm out of trade because of this thing

Sad man.

Straight from the Help section:
Scoring notes
Incomplete rosters will NOT add any points to your teams's fantasy total.

So you messed up and will have to roll back (if possible) or have to wait until Thursday.

Yes, indeed you need to have players in all the spots. If you configure your rosters and your get to a point where you can not buy a player because you do not have money anymore, you should press the Undo button.
That will leave your team as it was initially and you can reconfigure your team again.