each single-user license is just that, for a single user and cannot be (legally) shared between two different users.
cc programs can be installed on pc or mac. each user can install on an unlimited number of computers, but can only sign-in to, at most, two computers at any one time. those 2 computers can be 2 pcs, 2 macs or one of each.
klad, Thank you for your response. It's helpful.