You can find your silent installer here.

Go to management > management profile > install pkg

then go into PKGs upload the pkg file and click ALREADY HAVE A .PKG

After uploading the pkg file create a profile in the PROFILE tab with the configuration mentioned in the screenshot make sure you create a device group and add it to the profile.

Once you save the profile, the installation process kicks off as the profile pushes the update to devices added to the device group.