Most tournaments hosted by G-Loot require you to check in prior to competing in a match. The reason for this is to make sure that everyone is online and ready when the tournament starts. The check-in button can be found in your schedule in the left side menu on the G-Loot website.
In Team Party tournaments, only the captain needs to check-in for the whole group. In Mixed Party tournaments, every member of the party will need to check in.
The tournament details will tell you how long the check-in period is before the event starts. It is important that you make sure you and your team are online and waiting to start the tournament.
If you do not check-in in time for your event, you may not be allowed to compete.