Hello Nicole,
If you wish to use your SD card instead of the recommended USB & using a computer methods, you will first need to identify how you configured your SD card when first inserted.
If it was not configured for portable storage then simply moving the SD card over to the other tablet should bring your data & apps to the second tablet as it was configured for expanding the internal storage.
Take a look at this video here on how to configure an SD card and let me know how yours is configured if you see the option to format as portable at the bottom of the SD card icon on the storage menu in settings then you will have to format the SD card before it can be used to move data between tablets.
You may be better off using an app such as Dropbox or Google Drive to sync your .pdf folder to the cloud then sync using the same account on the second tablet.