For Bluetooth pairing no additional software is required, it is fully handled by Windows.
There is no need to install the Magic Utilities to pair your device.

Select your Magic Mouse model:

Prepare for pairing

For fastest pairing, turn off Bluetooth on all other nearby devices.
This includes mobile phones, laptops and desktop computers as well as Bluetooth speakers.

  • Make sure you have 2 fresh AA batteries inserted at the bottom of your Magic Mouse.

Bring your mouse into pairing mode

  • At the bottom of the mouse, turn your Magic Mouse off and back  on again.
  • Wait until the little green light above the power switch is blinking.
  • Make sure your Magic Mouse 2 is charged. A new mouse is already charged by Apple otherwise charging for 10 minutes is enough.

Bring your mouse into pairing mode

  • At the bottom of the mouse, turn your Magic Mouse off and back  on again.

Pair your Magic Mouse

  • Double click the Bluetooth icon in the Windows taskbar. If you can't see the Bluetooth icon,
    click on the + symbol below for detailed instructions.
    • Click on the little up arrow on the right side of the taskbar.
    • If there is still no Bluetooth icon it might be removed from the taskbar icons.
    • Search Windows for Bluetooth settings or Add a device or refer to your Windows Help System on how to add a device.
    • On Windows 10 select Settings > Devices
  • Select Add Bluetooth or other device.
  • Select Bluetooth.
  • Select your Magic Mouse from the devices listed, it can take a little while until the mouse appears.
  • Follow the instructions.

If a numeric code is requested while pairing enter 0000.

Verify pairing

In Windows 10, sometimes your device is paired, but is not working.

In Settings > Devices make sure your device is listed in the Mouse, keyboard & pen section.
If it's listed in the Other devices section it won't work.

Here is what did help:

  • Delete your device from Other devices and wait a bit.
  • Disable the Bluetooth radio
  • Enable the Bluetooth radio again.
  • Pair your device again.
  • Double-check if it's now appearing in the Mouse, keyboard & pen section.

Once the Magic Mouse is paired it should work as a generic mouse.

Moving your mose moves the cursor. Left and right clicks can be performed by clicking the left or right side of the mouse.

If you can move the mouse pointer on the screen it's time to install the Magic Utilities.

Note: If pairing doesn't work in the first place, installing the Magic Utilities does not help either.
In case you have constant Bluetooth issues, follow this comprehensive guide.