Yes, you need a smartphone that has NFC technology to use the CGM provided. Luckily, most smartphones sold since 2016 already have NFC technology embedded in them. So, if you bought your smartphone in 2016 or after, then you are probably good to go - our support team is always here to help confirm, or we recommend checking with your personal device carrier.
As a general rule of thumb, if you have an iPhone 7 or newer, a Samsung Galaxy S6 or newer, a Google Pixel 1 or newer, then your phone will work. Unfortunately, neither the iPhone 6 nor the iPhone SE (older generation) is NFC compatible.