No official, legal, free PDF of the complete Diccionario de uso del español (María Moliner) exists for download, as it is a copyrighted work. The “Writer” likely refers to a tool (e.g., Adobe Acrobat Writer) rather than an author.
: The dictionary includes detailed information on verb construction, syntax, and prepositional usage. Etymological Foundation
Diccionario de uso del español : María Moliner - Internet Archive