My Xbox store app was downloading and I pressed cancel installation and now it won’t start....

Hi. My name is Brilliant, and I am happy to assist you today.

Here are a few troubleshooting tips you can try to resolve your query:
- Restart your device.
- Update Windows.
- Update your device drivers.
- Update the Xbox and Gaming Services apps.
- Sign into the Xbox app and Store using the same account.
- Remove and reinstall Gaming Services.
- Make sure your date and time is correct.
- Disable your antivirus.
- Use the app troubleshooter.
- Repair and reset the Xbox app.

For more details on the above and more troubleshooting tips, kindly visit: https://support.xbox.com/help/games-apps/troubleshooting/troubleshoot-games-windows-10

I hope this helps resolve your query.

Sorry to hear it. As this is the beta app there are still issues to be fixed. If you are unable to download the game from the app then cancel it and open the Store App from the start menu and find the game there to install

When I canceled and used store app to download the game, I started and stuck at 24% again

This is a method which has worked a few times on my scratch GTA V disc which gets stuck at 16%. Start the install, go to the Xbox live store, and go to the game your installing. Your see the display that normally says Buy game, or
Download/Install, will say the progress of the install instead. When the disc fails to read, go to Games and Apps without closing the Store (i.e. through the Home button options). Eject the disc while the install is still paused. And then cancel the install
through the Games and Apps. Press B till you return to the Xbox live store that should still be on the game you where installing. Now the option is “Download”. Press it and the game downloads as if it’s a digital copy.

I can’t confirm this works on anything but GTA V, I do know however you will still need the disc to launch the game as it picks up on the fact you don’t digitally own it if you try to launch without the disc.

Sorry to hear it. If you are having trouble downloading the game from the beta app then please cancel the install and launch the Store app. Find the game there and start the install again

press WIN+R (Windows logo key + R) , Enter "services.msc", Right-click Delivery Optimization, Start, service indicates Running status

Canceled pending installations in Xbox app then try installing the launcher via MS store app.

If that did not work, press (WIN+R -> gpedit.msc)

Computer Configuration > Administrative Templates > Windows Components > Delivery Optimization

Activated "Download mode" and switched to 1.