While using a shared team email box for accessing the Event Maker is certainly possible, doing so comes with some risks. One member may accidentally change something without remembering to notify the other, two people may accidentally make conflicting changes or nobody remembers to check the notifications and critical information falls between the cracks.
It is recommended that each team member users their own account and are added as Staff members under the Organiser account.
Once you have set up your organiser account log into your profile
Then you see a summary of the organiser accounts you are a part of
If you are helping multiple entities to organise their 3x3 events, you should set up each one of them separately as organisers. You will still see all these accounts under your profile but you can then assign different people as staff for both organisations.