What's the date on the book? I assume it's of recent vintage (20th century), given its survival at the side of the road. Companies engaged in tropical development (and product extraction) in more recent times were not at all the major trading companies of old; this might be a concessionary company of newer vintage, connected to the developmentalist aspirations of Salazar's Estado Novo, but it may also be a state-focused trade association. Timor as a whole was often just a trading post, but it was always a crown colony in terms of governance if memory serves--often subordinate to Macao or Goa (India), especially into the late 19th century, but not always. Its formal administration became more regular with the division of the island between Dutch and Portuguese claims, and the final push of high imperialism generally. But I may be mistaken, so please correct me if there are unusual convolutions to the private-public relationship of commerce in Portuguese Asia.

Might the name be this one, the Associação Comercial Industrial e Agrícola de Timor (ACAIT)? (Link in Portuguese)--they handle business development and serve as something of a central repository, which would explain the presence of a library. It might also be a book they would want back, too--someone could have dropped it.