You'll need to phone SBTPG's live support during business hours for more info.  I'd also ask them to verify the email before uploading anything, just to be sure it's legit.

You may also be able to log in now to your temporary account at the SBTPG website to get more info, or their 24-hour automated phone may tell you more info.

To log in, choose the taxpayer portal at:
https://cisc.sbtpg.com

 Here is the SBTPG contact page.  At the page below scroll down about half way to see the Live Support number and 24-hour automated support number.

Live support hours at SBTPG are currently  7AM-4PM Pacific (10AM-7PM Eastern) Monday-Friday.

https://help.sbtpg.com/hc/en-us/articles/230084587-Contact-Information