É possível que essa funcionalidade esteja obsoleta (ou pelo menos não esteja disponível para usuários gratuitos).
Please note: We have a new, better way to share links to files and folders from anywhere in your Dropbox! Now all you need to do is select Share link from your computer, phone, or tablet. Quickly share anything with friends and colleagues—even if they don’t have Dropbox. Learn more here or go to this article to see how it works.
Because of this new sharing model, Dropbox accounts created after October 4, 2012 no longer have a Public folder. Don't worry! Every account created prior to this date will still have a Public folder. If you'd like to enable a Public folder on a new account, see the instructions below (Creating a Public folder) to learn more.
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Dropbox links give you everything you need to share and preview files and folders. However, if you’re just a diehard fan of Public folders, click here to enable one on your account. Currently only Pro and Dropbox for Business users can enable Public folders, so you may have to upgrade first. https://www.dropbox.com/help/16
Dito isso, ele ainda não o impede de replicar a funcionalidade 'Pasta Pública', criando um arquivo HTML simples que contém links para todos os arquivos relevantes que você pode querer compartilhar via Dropbox ....