The configuration required for Exchange/O365 is covered in the TMSXE deployment guide you have linked in your post, all the steps needed are in the guide. Conferences will start and stop based on the times it is scheduled in TMS via Outlook/TMSXE, allowing anyone to join and leave during that time. Recommend you also take a look at the TMSXE User Guide as well, it contains information regarding the booking process to schedule a video conference with TMS endpoints.