Pre-installed Kindle Scribe browsed doesn't allow you to download PDF files.
So you have to download the planner to your laptop or Apple/Android device.
Then visit the official send to Kindle page
https://www.amazon.com/sendtokindle
to upload the file, and install to device
You have to find it on Kindle, look at the "Recent" on the "Home" tab
Also, take a look at our Digital Planning Guide:
https://onplanners.com/digital-planning-guide#kindle-scribe