Save the PDF to your device first. If your download is a ZIP, extract it and choose the PDF inside. Import the file itself, not a screenshot or a printed copy.
Kindle Scribe
Open amazon.com/sendtokindle in a browser. Sign in with the Amazon account used on your Scribe and upload the PDF. Connect your Scribe to Wi-Fi, sync, then download and open the document from Library.
Use Send to Kindle for this setup, rather than copying the file by USB.
Open Send to Kindle→iPad + Goodnotes
Save the PDF in Files. In the Goodnotes library, choose New > Import, then select the PDF. Import it as a new document. Use Apple Pencil to write.
Goodnotes import guide→Samsung Tab + Samsung Notes
Save the PDF on your tablet. In Samsung Notes, touch and hold Create note, then choose Import PDF. Select the file and tap Done. Open the note and write with your S Pen.
Samsung Notes import guide→