Hi thank you for your post here on the Zoom Community! It could be that your waiting room settings are allowing anyone in the meeting to add people rather than only the host being allowed to let people into the meeting from the Waiting Room.
If you can sign into https://zoom.us and in the Personal Section in the upper left, if you click on Settings, then scroll down to the Waiting Room section. Here you can see all your Waiting Room settings, I believe once you tweak those you will be good to go! This is a screenshot to help you know where to go, you will see the section "Who can admin participants from the waiting room" and I believe this is an important one, but have a look at all those settings:

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