In answer to your question of how to view private Instagram profiles on a mac, there is currently a lot of rumour about how you wpuld hack Instagram 0 but not much fact.
What is clearly lacking, is a general understanding of the set up, so let me break it down for you:
Hacking private Instagram profiles on mac computers (or any computer for that matter)
Instagram is bound by privacy laws to protect it's users, therefore if a user has specified that he or she wishes to make his/her posts unavailable to users that they have not accepted on to their account or to the general public, Instagram is legally bound to protect this.
This means that you can not see a private account without following it.
One option could be to request to follow the account. If the user is not hugely concerned with who follows them, they may accept your request regardless of whether they know you or not.
Otherwise, there is currently no other way of seeing a private instagram profile on any device.
I hope this helps.