How do I handle my open container citation in NJ?

Was ticketed for open container in a vehicle a few days ago. I was unaware that there was an old, empty beer bottle stuffed in the back pocket of the front passenger's seat. The physical citation does NOT have the "mandatory court appearance" box checked. But the online payment site says I cannot pay my $0 fine and must contact the courts. Was discovered after an officer looked into my car during a traffic stop for speeding at roughly 2am. Please Advise