Currently, the teams feature is only open on upgrading to the business plan, though my team does not require the business plan currently since we are in the nascent stage of moving from Asana / Jira to Click Up, while we might not need everything from the business plan, the teams feature is such that it holds importance to every business and makes life easier for tracking and assigning and I believe if not included, it should be like Automations are (if more than 1000, then Pay per use), similarly, you can introduce the plan for teams as well.