You should at least try to convert to the 2013 version since you don’t use any online services or download transactions now. Then it should run on newer versions of Windows. Starting in 2014 they instituted an ID password to get into your own data. I’m staying on 2013.
2013 should run on Newer Windows. You can download 2013 Deluxe for free using this how to convert article. It’s under Converting from Quicken 2004-2009.
If your version is 2003 or earlier you will need to first convert to 2004. Then convert to 2013. Read that whole article on converting.
And FYI - If your Quicken was before 2010 you should have several files making up the data. The main data file ends in .QDF. All Quicken versions prior to QW2010 store your data in a series of files all sharing the same filename but with different extensions like - .QDF .IDX, .QEL, .QPH and all 4 of those files were rolled into a single-file .QDF starting in 2010.