The printable planner only requires a device (and software) that can open a PDF file. Most Apple devices (such as an iPad or Mac computer) and Kindles can do this automatically, however if you are using a Windows computer or Android device, you will need to get a free PDF reader (such as Adobe Reader).
The digital version is an interactive PDF, not an app. You’ll need to open it in your own note-taking apps, such as Goodnotes, Xodo, ZoomNotes or OneNote. Please note I am not affiliated with any of these apps and can only provide support relating directly to the planner.