Anyone can use Pubget to get PDFs that are publically available. However, since most PDFs are still available only by subscription, you are likely to be able to access much more if you connect through a university or other subscribing institution with which you are be affiliated.
If Pubget supports your institution, you can set your institution through the "Settings" menu. Keep in mind that some institutions offer access only from on-campus locations.
If Pubget doesn't support your institution, click here to find out how to subscribe. Pubget is able to support institutions in Europe, Asia, Africa, Australia and Oceania, and South and Central America, as well as in the United States and Canada.