Engagement and attendance are different, but connected. Attendance will be taken for all online and face-to-face sessions. That means you've logged into Zoom or have personally attended a session. Registering for classes is your attendance
Engagement means, are you asking questions you need to ask, are you answering questions asked of you, or helping out your peers in the chat, have you done tasks that have been set for you - that's engagement and we can track that through Canvas Analytics and face-to-face interaction.