Shared Apps with Two Accounts

[pectin232]

I have a macbook air shared by 2 person. Admin 1 and Admin 2. some apps are shared which 1-2 are not which are like Emails. They are using by different mgrs from a dept but that laptop is for receiving email and resolving support problems from emails from different regions request help. MS word and excel and 1-2 other apple apps are shared but emails are not. How do I avoid reinstalling MS office 2016 for 2 users (save the HD space as there is only 128gb drive and not a 512 or so.