Open block Menu by clicking on Large + button (see the image below)
2. Click on Widget (Left side) and then Choose PDF widget from available sections
3. After adding the PDF widget a default PDF file will appear, click on the PSD and then select Edit Widget
4. you can upload your PDF file to any public cloud like Google drive, Google docs, Amazon S3 etc. and get the link to your PDF file.
Enter the Link to PDF file in File URL column and Click on UPDATE button