Quicken Medical Expense Manager has been discontinued a few years ago, so there's surely no official support for Windows 10 systems. However, if you still have a working version of the application, there are a few workarounds that you can try.
The easiest solution that you can try is to right-click the executable and go to Properties. In the window that opens up, go to the Compatibility tab, then tick the box marked as Run this program in compatibility mode for and select the version of Windows you were previously using. Lastly, tick the Run this program as administrator box, click Apply and then OK.
In case this didn't solve the problem, you can always create a virtual machine, install an older Windows version there, then setup the application. If you don't know how to use virtual machines, check out this article.
