From Zoom:

Starting July 19th, Zoom will require that all meetings have a Passcode or a Waiting Room enabled. 

We have designed these security measures to give you control over your meeting security options while keeping the join experience as frictionless as possible.

• For meetings that do not have either a Passcode or Waiting Room enabled by July 19th, Zoom will enable a Waiting Room for you
• You can customize the Waiting Room experience with an approved list of domains that can bypass the Waiting Room and directly join the meeting
• You can find meetings that are scheduled without a Passcode by pulling the following report 
• For meeting join information, we are renaming “Passwords” to “Passcodes” to better align with its role of allowing people in a meeting

For more details, including a comprehensive FAQ document, please visit our Support page. If you have additional questions, please reach out to your Customer Success Manager or our Support Team.