Your new Windows version doesn’t support DOS applications anymore.
Previous Windows 32-bit versions included NTVDM, facilitating DOS programs to run. Windows (10) 64-bit is now the norm: Starting a DOS program will only display a popup it can’t run…
…Microsoft dropped 16-bit (so also DOS) support in 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 even out of business. Despite Windows versions/alternatives, you may prefer using that 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.

vDos lets you conveniently run DOS applications by emulating an extended DOS PC in a window. vDos itself runs on Windows 7 or later, 32 and 64-bit. It will be the only adequate solution for using serious DOS programs.

If you however don't still use (so 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!
vDos highlights.
DOS applications start instantaneously in a scalable window and 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.
No-nonsense, focuses on serious end-user programs, setup yours easily. No tricky configuration to load drivers, set file handles, keyboard layout, language character set…
Run 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, 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.
Small footprint, little impact on Windows resources. Not advertising its presence, except if unregistered and networked.
vDos by JHM Schaars - The Netherlands - CoC registration 09103086