Facing a problem in first time login

If login is first time.Then see below and follow that instructions

yeahm i have also heard that some of the users unable to login. While doing first time login they are saying that "Provisional ID / GSTIN / UIN entered is already mapped to a username. Kindly login with valid username.." 

and

IF we use forgot username, then message is coming that "Username is not created. Kindly contact your jurisdictional tax office to obtain username and password"

Dont know what type of problem they are facing.

How did you reslove this issue ?

I have registered as a new Tax Payer and I received the Username and Password Last day. I have tried to login with the gst portal to download the Registration Certificate. but system shows Provisional ID / GSTIN / UIN entered is already mapped to a username. Kindly login with valid username ...how to reolve it

I was facing the same problem, but it has been solved. Whenever there's a first time login, there is a link below that says,  If you are logging in for the first time, click here to log in.

click on that link and provide your details to login and set a new username and password. 

Did your problem got solved?