Unable to create "Ads creative post"

Response : Ads creative post was created by an app that is in development mode. It must be in public to create this ad

[maKabirkhan]

Response body: {"error":{"message":"Invalid parameter","type":"OAuthException","code":100,"error_subcode":1885183,"is_transient":false,"error_user_title":"Ads creative post was created by an app that is in development mode","error_user_msg":"Ads creative post was
created by an app that is in development mode. It must be in public to create this ad.",

I am having this issue while testing ads creative post in sandbox envrironment what's the solution?