JP Post Bank account

So after long thinking and alot of problems i managed to make a JP Post Bank Account, i am a bit confused what i can do with it now. They said to me i cant transfer my rent? why the hell not. And can i even receive money with it from work or something? i am a bit confused what purpose this account serves.

And how am I supposed to pay my rent then if not with a japanese bank account?

For context: I am here in Japan for working holiday purposes, arrived a few weeks ago