Using Google's Firebase with Seating Charts add-on is not mandatory but it is very handy thing to have. This will allow you to display in real time tickets that are in each of the site visitors cart. To be able to have this, you will need Firebase account which is free to use. You will need, of course a Google account for this so if you don't have one already, you will need to create it first. Once you're logged in to your google account, navigate to https://console.firebase.google.com/ and then follow the rest of instruction from the video below.
At one point of video instruction, you will be prompted to copy a snippet and paste it to the rules of your Firebase realtime database. Below is the snippet that you should use:
{
"rules": {
"reserved": {
"$chart_id": {
".indexOn": "timestamp"
}
},
"in-cart": {
"$chart_id": {
"$seat": {
".indexOn": "timestamp"
}
}
},
".read": true,
".write":false,
}
}