If you cannot receive SMS verification codes, please refer to ApolloX Supported SMS countries. If your area is not covered on the list, please enable Google Authentication, you may refer to the following guide for more details: How to Enable Google Authentication (2FA).
You may not be able to receive the SMS verification codes due to network congestion, please wait for 30 minutes and try again.
Also, you can follow below steps for checking.
Ensure that your mobile phone has good network signal, otherwise, please re-position to a spot with better signal;
Close Anti-virus and/or firewall and/or call blocker apps on your mobile phone that might potentially block our SMS Codes number;
Restart your mobile phone.