As long as you're added to the course as a Teacher, you should be able to start the Zoom meeting as if you were its host. Make sure you start the Zoom meeting from the Zoom Video Conferencing LTI (not the usual Video Classes LTI):
After you click on Zoom Video Conferencing, you may need to wait up to one minute and refresh the page before Zoom will add you as an alternative host and let you start the meeting.
If you still can't start the Zoom after that, please post a message in the #live-course-emergency Slack channel. The support team can troubleshoot or start the class meeting for you if needed.