If you manage multiple teams, you can add them all to your Teammo account. You don't need a new Teammo account for each team. To add a new team to your account, go to Teams in the menu.
Then, click + New Team and follow the prompts. For more details on adding new teams: http://help.teammo.com.au/en/articles/1379373-setting-up-a-new-team.
You can connect to your association via https://app.teammo.com.au/connect-team.