Publishers have the option to specify a list of email addresses when creating an invite widget--only accounts associated with those email addresses can access that book or audiobook via that widget link.
If you received an email invite from a publisher, but when you sign in, see an error message that "the publisher has not approved your email address for this title," it is likely that the email address you used to create your NetGalley account is different from the email address the publisher authorized.
To access the book, simply email the publisher and let them know the email address you have in your NetGalley Profile, and ask them to send you another widget link to download the book.
If you are having trouble, contact our friendly support team.