Authors and Admins can export Cards in bulk via the Card Manager.
Navigate to the Card Manager in Guru's web app on the top navigation bar.
Select the Card(s) you want to export by clicking in the checkbox(es) to the left of the Card title. Then click on the Export icon.
Confirm that you would like to export the selected Cards. Once confirmed, the exported Cards will be emailed to you for download as a CSV file.
Then, in Slab, go to Import & Export in your Team Settings. Next to Guru, click Import. Drag-and-drop or click to upload the CSV file emailed to you in the above steps.