First, are you sure you need a PIN from the IRS? PIN's from the IRS are by request only, and you'd have received it in the mail. It's not super common.
More often, people get their prior year AGI confused for a PIN, as it's required to e-file.
There's some good info on them here: https://ttlc.intuit.com/replies/3388576
If you're locked out and do need a PIN, you'll probably want to take an extension and file once you receive it.
