Creating User in esxi 6.5 and assigning role
I was trying to figure this out as well and found the solution. It's a little strange assigning the user permissions, as it's in a different location from the tab where you create users and roles.
If you got back the default host view and click on the Actions button on the top of the view and go to
Actions -> Permissions
From there you click Add User, and then pick the user account you created and the role you want.