Having trouble downloading the data

I am trying to download a data extract from IPUMS USA. When I click the Basic or DDI codebook links, I am shown a page that says “Not Authorized: No registration for product”. I am not sure why this is happening. I was able to look at the codebook of my previous extracts before and have never faced such issues.

Can anyone tell me how to fix this?

It appears that you never registered for IPUMS USA, but only IPUMS NHGIS. Each IPUMS project requires a separate registration (though most of your information will be pre-filled). Please log out of your IPUMS account, and then visit IPUMS USA: account options to register for IPUMS USA.