I'm attaching a copy of the user manual for you in pdf format. you can save it to your computer for future reference or print it out.
Page 7 of the manual explains Setting up your Bitbit Blaze. You can use a mobile device with the Fitbit app for iOS, Android, or Windows 10 mobile devices, PC Windows 10 with the same Fitbit app for Windows mobile devices, or PC Windows 8.1 and below using the wireless sync dongle. (meaning that you only need the dongle if you have a Windows version older than 10.) You will however, need to install the FitBit App.
Find the Fitbit app in one of these locations, depending on your device:
• The Apple App Store® for iOS devices such as iPhones and iPads.
• The Google Play™ Store for Android devices such as the Samsung
Galaxy S5 and Motorola Droid Turbo.
• The Windows® Store for Windows 10 mobile devices such as the Lumia
phone or Surface tablet.
This is from the Windows 8.1 and below section:
Note: Unless you upgrade to Windows 10, you’ll need to purchase a wireless sync
dongle from fitbit.com/store in order to set up your tracker.