I can't log in by touching the unit with my smartphone (NFC). Why not?

Please check the following.

[Internet settings]
・ Make sure the smartphone and the unit are both connected to the internet.

[Smartphone settings]
・ Make sure you've installed the latest version of rekordbox for iOS/Android.
・ For Android devices, check the device settings to see if the NFC function is turned on. 
・ Hold the NFC mark (tag) on the smartphone close to the NFC touch area on the unit and wait for a few seconds. If there's no response, slowly move the smartphone back and forth, left and right.
・ If you're using a smartphone case, please remove the case.
・ The communication sensitivity of the NFC function depends on your smartphone. If you have difficulty connecting, turn off the NFC function of your Android device, then turn it on again before approaching the unit.

【CDJ-3000X settings】
・ Check if the NFC login indicator on the front panel of the unit is lit or blinking. If the light is off, you can't log in to rekordbox CloudDirectPlay.

For details, see [rekordbox CloudDirectPlay] in the Instruction Manual.
You can read the Instruction Manual [here]（pioneerdj.com/support/documents/）.