To let your friends pick you from their address book, enter the phone number they can use to add you. Use international format, for example: +79261234567.
Enter your name that your friends will see. It does not have to match your passport exactly, but it should be recognizable to your friends.
If you do not allow the app to send push notifications, you will not be able to confirm registration via push. In that case, you can provide an email and receive verification codes there.
The lower field shows the registration option currently available to you (6, 7). If you entered an email but did not allow push notifications, registration will be via email. You can switch to any available registration option.
Tap "Register" and enter the verification code received via push notification or email.