Web - Server

I’m not good at English, so please understand generously !!
I already solved this chall, but I have question not clear..

I’m afraid this would be spoiler so If it is spoiler, tell me then I’ll remove it.

We send password for POST method, and by the title of chall, we can send something to server and we should satisfy the conditional statement.
at this point, why is sending parameter that chall want to receive with password parameter not correct ?

I mean, just sending parameter that chall want to receive alone is working, but sending that parameter with password is not working.

need help  😢

either do I stuck there.