Windows 64-bit doesn’t support DOS applications.
Windows 32-bit included NTVDM, facilitating DOS programs to run. Windows 64-bit is now the norm; w/o NTVDM or an option to downgrade to Windows 32-bit, starting a DOS program will display a popup it can’t run…
…Microsoft dropped 16-bit support (so also DOS) in all Windows 64-bit versions, not just recently in Windows 10!
To find a version for your PC, check with the software publisher.
That probably doesn’t help: The DOS application could be developed by yourself, a company not supporting it anymore, or out of business for years. Despite Windows versions/alternatives, you may prefer - even forced - using the DOS application for various reasons and time to come.

First option was to install a virtual Windows 32-bit system. The setup can be daunting, to 'only' run that DOS application, its use overkill and cumbersome. DOSBox is a popular alternative, but intended for gaming only. Certainly not to be used in a multi-user/network setting since it WILL in time destroy your database files.

vDos lets you conveniently run DOS applications by emulating a (spiced up) DOS PC in a window. vDos itself runs on Windows 32 and 64-bit systems, Windows 7 or later.

If you don't still use (rely on) a DOS application, want to play/experiment with DOS, its command prompt, programs or games: Forget about vDos, it is not meant for you!

Don’t just hurry to the Download page. vDos may not be what you’re looking for. 'Expert' reviewers mostly don't get it (at all), not actually testing DOS applications in vDos. With silly advices like “install vDos inside your Documents folder for files to be backed up and protected”. Frequent use of vDos may also cost you inconvenience or money, you don’t want to spent. Have a look at some other pages.
vDos highlights.
Starts DOS applications instantaneously in a scalable window with a crisp TTF font (in text mode). Actually delayed until the application is ready for input, so you don’t get a black DOS screen echoing startup commands.
Focuses on serious programs, setup yours easily. No tricky configuration to load drivers, set file handles, keyboard layout, language character set…
Runs multiple DOS applications (simultaneously), if needed with their own specific configuration. No conflicts with eventual Windows NTVDM instances running alongside (like in a mixed network).
Also prints to Windows-only (GDI) printers, or for instance a virtual printer to produce PDF’s.
Its file system is (in sync with) that of Windows, no internal disk caching corrupting files.
Network support with file- and record locking, required by multi-user DOS applications to function reliable.
Copy/paste text from Windows to DOS and vice versa, with transparent conversion of Windows/DOS text.
Little impact on Windows resources, effectively unnoticed. Not advertising its presence, except if unregistered and networked.
vDos by JHM Schaars - The Netherlands - CoC registration 09103086