So nothing actually arrives when you export it as a pdf, unless you are taking about sending the file via email for which I apologize in advance 
When you export the project as pdf you initially get this message.

Post this step, you need to wait for some time to get a message which says that your project can now be downloaded.

Once you click on the link (your project name), a pdf version opens in a different tab. But I think the download button here is broken. The file is saved in a unknown format.

Workaround: Open the project is crome and press "ctrl+p" (print command). Select the destination as "save as pdf" and hit go.

Works like a charm. Let me know how it goes.