Hi Chirag,
If you have applied for the Beta you would have got the confirmation mail from twitter stating:
Your Twitter developer account application has been approved!
Also, in the same mail, they have mentioned the App ID which has the access and Env name which will be used in end URL
If you still have doubt you can ask Twitter staff with the App ID they can let you know
Let me know the end URL that you are using
Cheers,
Sagar