Right now it only has two Bible translations – KJV and ASV – KJV includes these books, but in this website's copy of it they are missing. In the KJV, they were relegated to a separate section called the "Apocrypha". Catholics and Orthodox oppose that name, and that segregation. Protestants viewed them as having "lesser authority", primarily on the argument that Jews do not consider them to be scripture. By contrast, the Catholic Church declared the Deuterocanon to be of equal authority to the rest of the Bible at the Council of Trent, and many Orthodox adopt the same view.
Starting in the 19th century, there was a movement among Protestants to exclude these books from the Bible entirely, rather than simply relegate them to a separate section as previous generations of Protestants had done. As a result, the majority of contemporary Protestant Bibles omit them. Even the majority of contemporary printings of the KJV are missing those books, although in doing so those printings are being inauthentic to the intentions of its original translators and editors.
The other translation this site has, the ASV, is an early 20th century American revision of the late 19th century English Revised Version. The English Revised Version included the "Apocrypha" section, but following this movement against these books among Protestants, the ASV excluded it. (A minority of printings of the ASV do include an "Apocrypha" section, but that is taken from the English Revised Version, it did not form part of the American revision process.)