The main purpose of this scam is to trick people into entering their Microsoft account credentials so that the scammers responsible can steal their accounts. The second PDF document contains yet another link, which opens a fake Microsoft sign-in page.
This link then opens a Dropbox page that contains another PDF document. This email contains a link designed to open PDF document, which contains a Dropbox shared link. It is just one of the many cases whereby scammers exploit the name of a well-known company or organization to trick recipients into believing that a received email is official and legitimate. To make this phishing email seem more believable, scammers disguise it as an automated email from Dropbox. Therefore, do not trust this scam email and, more importantly, do not enter information on the deceptive website.
This document can be opened through a link within a phishing email. They try to deceive people through a link within a PDF document, which is downloaded through a Dropbox shared link contained within another PDF document. Scammers behind this phishing scam attempt to trick unsuspecting recipients into providing their Microsoft account credentials.