This is OneNote 2016 (desktop version, NOT the app).
Though this is still available in 2019 as a downloadable installation, Microsoft
are making it harder to find, and I suspect at some point it will no longer be
supported. Here is a the offline installation, so you can still install it, even
if it is dropped by Microsoft.

HOW TO INSTALL ONENOTE 2016 (off-line installer)

1. Identify whether you want to install the x64 (64-bit) or x86 (32-bit) versions.
If you have a 64-bit operating system, you can install either version.
If you have a 32-bit operating system, you MUST install the 32-bit version
To check which type of operating system you have: <Win>-X, Y, and under
Device specifications check the System type.

2. Open a CMD prompt (Windows-key, type "CMD", press enter)
Change your directory to where the Setup.exe is located, eg.
CD "C:UsersdavidDownloadsOneNote 2016 offline installer (x86 and x64)", then

FOR 32-bit install, type:
setup /configure configuration-OneNote2016-x86.xml

FOR 64-bit install, type:
setup /configure configuration-OneNote2016-x64.xml

FURTHER INFORMATION
-------------------
This package actually contains the offline install for the entire Office 2016 suite,
hence the 3.55GB package size. It will however, using the provided configuration
files, only extract and install OneNote 2016 free edition. MS does NOT list
'OneNoteFreeRetail' as a Product ID in their Deployment notes, but it works anyway.

It is possible to install other Microsoft Office applications off-line as well, by
editing the appropriate Configuration_xxx.xml file, but there are easier ways to do
that. Also you would need valid activation keys to use them once installed.
To read about Configuration options for the Office Deployment Tool (which is what
Setup.exe is), check this Microsoft page:
https://docs.microsoft.com/en-us/deployoffice/configuration-options-for-the-office-2016-deployment-tool

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Installation package courtesy of: Dementia Software
Thanks to tdallison for doing the original research
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