“Please wait a moment while we launch our security service” is caused by Zscaler trying to authenticate you for Internet access.
Go to https://ip.zscaler.com/ to check your current status.
From my own testing, Postman didn’t initiate an Internet connection that triggered SSO authentication with Zscaler.
It’s unlikely your IT network security team will allow unauthenticated access to Postman URLs to workaround this problem.
Also, have you set HTTP_PROXY, HTTPS_PROXY, and NO_PROXY environment variables to match your corporate settings?