I use W11 and it is working with online multiplay, Did you see the guides for fix it? I recomend this: https://gtm.steamproxy.vip/sharedfiles/filedetails/?id=1904501479

Mortal Kombat Kollection Win10 "Press Enter" issue
Issue:
the game will not go beyond the "Press Enter" screen.

Solution:
1. Uninstall “Microsoft Games for Windows – LIVE Redistributable”
2, Uninstall “Microsoft Games for Windows Marketplace”.
3. Restart system.
4. Download two GWFL files: xlive.ini and xlive.dll from this link: https://www.dropbox.com/s/be930uac7fnsiuf/MKAK_fix.rar?dl=0
5. Place the two files into your MKAK install directory. The default should be C:\Program Files (x86)\Steam\steamapps\common\Mortal Kombat Arcade Kollection.
6. Start the game ONLY from Steam (directly launching "MKHDGame.exe" will not work).
7. Enjoy the game

Notes:
- Do not set any compatibility with any previous windows versions
- Do not install GfW (Games For Windows)
- Launch game ONLY from Steam

this works thx