I have a question that I have a problem when I want to upload a file through Gen3. It said that I don't have permission to access the website to do that. So what is my problem and how can I fix it?
Welcome to the forum! 
Where you try to upload a file? Do you use Compose Services or Cloud Automation? Could you provide steps you are doing so we could understand better what is going on and how we can help. An error log and a screenshot would also help.