Simulate access isn't controlled by which Role a user is assigned — it's controlled by specific permissions on that Role. There are two separate permissions involved, so check the one(s) that match what you need:
Author Coaching Content — lets someone create and edit simulations/scenarios.
Assign Coaching Activities — lets someone assign a simulation to a user. This is a different permission from Author Coaching Content — a role can have one without the other.
How to grant it
Go to Settings > Roles.
Find the role your user already has (e.g., "Lead," "Supervisor," "CTO") and click to edit it.
Under the Coaching permissions group, check Author Coaching Content and/or Assign Coaching Activities, depending on what you want this role to be able to do.
Save. You do not need to change which Role the user is assigned — only the permissions on their existing role.
Note on timing: the change takes effect the next time the user logs into or interacts with Simulate, as long as it's been at least a few minutes since their last Simulate session. If they don't go back into Simulate, the change won't apply until they do.
If a user without the Assign permission tries to assign a simulation, they may see an error rather than the option being hidden — if that happens, double check the Assign Coaching Activities permission on their role.
Note: If you want this ability limited to a smaller group than everyone who currently holds a given role, create a separate role with these permissions and assign it to just that user instead — see Modifying a User's Role in CommsCoach.