the vendor account you entered is not associated with the item you are trying to open

I tried to open my bought eBooks in Digital Editions on a new laptop, both authorised with my Adobe ID. Now I can't read the eBooks on the new laptop due to the following error on authorisation:

the vendor account you entered is not associated with the item you are trying to open

I tried to the Adobe online chat, who said to post here. I tried their Twitter account @AdobeCare who also said to post here.