It’s hard to cover this question for every type of phone, but here are the basics:
iPhone/iPad– tap to open the Digital Workbook in your browser, then tap the share buttonand open it in the Books app. You will able to fill it out and it will save your progress. Alternately you can tap the share button and save it to your files and download an alternate PDF Filler app from the app store.
Android– Tap the three vertical dots icon on the top-right. Tap Print. Tap Select printer. Tap Save as PDF. Tap the Save icon. Now you can select the place where you want to save the file and tap Save. Download a PDF Filler app from the Play Store and open the file in that app.
Click to open the Digital Workbook PDF
From the File menu of your browser, select Save As… and choose a location on your computer to save the file.
Use a program such as Adobe Reader, Preview (Mac), or Windows default viewer (generally speaking the program your device automatically opens it in will work). Fill out the PDF and save.