In part, permission setting instructions/descriptions say this:

6. Grant the proper access to .....

'admininister all signups':
Implies 'view all signups' and 'cancel own signups' permissions.
Allows users to view who has signed up for nodes, to cancel
signups of other users, to close signups for specific nodes, and
to configure system-wide settings related to this module.

'administer signups for own content':
Allows users to view who has signed up, to cancel signups of
other users, and to close signups for any nodes that the user owns.

'cancel signups':
Allows users that can administer signups for a given node to
cancel the signups of other users from the node/N/signups page.

And...
Viewing the signup report (Administer > Content management > Signup),
and configuring the module (Administer > Site configuration > Signup)
are restricted to users who have the 'access administration pages'
privilege.

1 - the 'cancel' perm description seems to contradict both 'admin' perm descriptions - or at least calls to question whether 'cancel' is required in ADDITION to 'admin' for users you want to be able to cancel signups - because:
- - A - both 'admin' perms seem to already grant "cancel signups of other users" rights (to all or only their own nodes).
- - B - 'cancel' perm seems to only add a permission for "users that can administer signups for a given node" - HOWEVER, if they already have 'admin' perm, what would 'cancel' perm add?

2 - "Viewing the signup report" portion should nore properly read:
To view the signup report (Administer > Content management > Signup),
and configure the signup module (Administer > Site configuration > Signup)
requires both the 'access administration pages' and the 'admininister all signups'
privilege.