about send postfix ,why can only send 100?

limit per user to send email is 10,000 messages a day. But why I had sent 100 messages and has a limit? postfix test prompt:550-5.7.1 Daily SMTP relay limit exceeded for customer.

gmail messages auto-forwarded? send? I do not understand how to send a daily 10000 G SUITE account

I use postfix settings, relayhost = smtp-relay.gmail.com can only send 100 messages a day, I am a G Suite Business account.

help me! !