[kwhitefoot]

Doesn't work for me with Firefox 82.0.3 (64 bit) on Win10. Hitting the Read Book link just gives me a blank window with the Close Book link at the top.

Took me a few moments to realize that this is because my Firefox is set to download PDFs instead of displaying them in Firefox.

[resdev]

Thanks for letting me know. Hopefully you can at least access the pdf by downloading. Just so you know, the pdf display embed only works in desktop screens etc., mobile screens would open pdf in a new tab in mobile browser. This is because pdf embed within app makes text to be too small for some readers.