There is a function in Xert that supports scheduling a group session where multiple users can join and ride the same session at the same time. The session starts at the scheduled time automatically. In this case you’ll notice a countdown timer if you start EBC within 10 minutes of Start Time. If you (or others invited to the group session) miss the start you’ll see Join a session In-progress.
To avoid this issue, I suggest you use Play Now right before you are about to ride a workout which queues that workout for selection on EBC. The workout doesn’t actually start until you tap Start on EBC which in turn restarts the Remote or Session Player from the beginning.
Lots of newbie tips are posted here –
Onboarding steps for Xert trial users and newbies - General - Xert Community Forum (xertonline.com)
Welcome aboard. 