You are entitled to watch all the videos on this youtube channel https://www.youtube.com/@DavidOsee-English

Also look through this https://gist.github.com/chaiwa-berian/5294fdf1360247cf4561c95c8fa740d4?permalink_comment_id=4029850

  Happy coding

Am tired of MTN, can you imagine a project that was like, now we are getting : Access denied due to invalid subscription key. Make sure to provide a valid key for an active subscription.

What language are you using to call the api. You must understand most of the issues you are facing is compliance. Read the documentation. Watch the onboarding videos. You are not the only person using this gateway...