The MEETS platform is a secure platform, and all Webex meetings scheduled within MEETS have passwords. The meetings open seamlessly with the platform sending the password directly to the meeting without a need for the user to do so. This allows for ease of use along with security.
When using an iPhone or iPad, to assure the app opens Webex and allows one to join the meeting without requesting a password, assure that the settings do not enforce desktop websites on all websites.
Go to Settings>Safari>Request Desktop Website and assure that "Request Desktop Websites on All Websites" is turned off.
As above, if the setting is to have it on, when one joins a Webex meeting, it will request a password.