please fix that error

it havent worked for 1 month it shows {"code": 403, "error_type": "OAuthForbiddenException", "error_message": "You are not a sandbox user of this client"}

ayajeksidkcjcjdjdjaiqlwkdhe about Followers Mania for Instagram - follow management tool with statistic about likes and comments for true IG, v1.2.2