I am on two parallel plan but unable to add more than ten users. Why can't I add another?

I am on two parallel plan and I am trying to add a user. I am not able to do that. I already have 10 users in my account. Why can’t I add another?

Hi Macy!

As per your plan, you can add a maximum of 10 users in your account including you. If you want to add more users, you need to upgrade your plan.