ZingGrid doesn't currently support a direct export to PDF option (we have made a note it as a feature request). Here's more info on the export options ZingGrid does offer: https://www.zinggrid.com/docs/features/exporting-data.
If you specifically need a pdf export, what are the requirements of this pdf? There may be some workarounds that satisfy your needs:
Server - You could take an image of the grid and import it into a pdf with puppeteer: https://github.com/GoogleChrome/puppeteer
Client - You could read all grid data and recreate the grid in a pdf library like: https://github.com/MrRio/jsPDF
If you provide more requirements, we can better serve you, and it will help us integrate a future solution for you and our other users.