The URLs for the epub & mobi files are borked because they include the domain name twice. These links should work:
Correct EPUB link:
http://giganotosaurus.org/ebooks/2019/Hunger%27s%20Truth%20-%20AJ%20Fitzwater.epub
Correct MOBI link:
http://giganotosaurus.org/ebooks/2019/Hunger%27s%20Truth%20-%20AJ%20Fitzwater.mobi