If the Options menu in the top-right corner is labelled with the word “Unregistered” instead of with your username or email address, it means you are using Texidium as an unregistered user.

Unregistered users can access their books through the site where they were obtained and read them in the online reader without creating a Texidium account. However, unregistered users cannot sign in to Texidium directly, download books to a device, or read offline. To unlock the full functionality of Texidium and your eTexts, it is recommended that you become a registered user.

Unregistered users can register by clicking Register in the drop-down menu under the word Unregistered.