All members, regardless of their role, can be eligible to play. To be eligible, they must have the required information, e.g. the Ubisoft Connect ID, stored in their profile.
However, each event may have additional conditions for eligibility to play.
The eligibility to play in an event is represented by green or red circles. If a player is eligible to play, the circle is green.
If he is not eligible to play, the circle is red. If you hover over the red circle, you can read the reason for it.