Once you hit the "Export" button, the pop-up window will offer you a few options.

Quick export - file is ready and downloaded instantly to your PC (1000 rows max).
Full export - it will prepare a full export depending on the limits of your subscription (but might take longer to process).
Custom export - you choose the number of rows to be exported.

If you decide to export more than 1000 rows, it might take longer in comparison with a quick export. Once your file is ready, just click on the Exported files button next to your account and there you can see your file ready to download.

Note: Your download links are stored for 7 days from creation.

Tip: If you use the option "Send e-mail when export is complete", you will receive an email in your inbox, once your report is ready.