What version of indesign?
If you have adobe creative subscripiton or indesign cc it can install of two different OS system.
Yes. One license can be used on max. two machine(OS doesn't matter).
That is only true with Creative Cloud. For earlier versions, while you got
two installs and activations you only got one platform.
And in any case the license is for a single user to work on either machine, but not both at the same time, and most definitely not two different users.