How to import my previous accountant's (now passed away) previous years' turbotax files into my laptop so I can bring them into my own turbotax software?

My accountant, who did my taxes for years using turbotax Home & Business, recently passed away. Her son provided me a memory stick with previous years of turbotax filings contained on it. How can I utilize this information and pull it into the 2018 turbotax Home & Business software that I will install on my own laptop? Do I need to first install both the 2016 turbotax Home & Business and the 2017 turbotax Home & Business programs first, then download my accountant's data into it, and then, finally, install the 2018 version and import from those other two? I'm not familiar with how any of this really works so please forgive my ignorance.