Source: https://www.ni.com/docs/de-DE/bundle/whats-new/page/change-ni-help-preferences.html

To use the NI Offline Help Viewer, you must first change your NI Help Preferences to disable the use of online help.

1. From the Windows start menu, navigate to National Instruments » NI Help Preferences.
2. In the NI Help Preferences window, disable Use online help.
3. Click Apply.
4. Launch the documentation from the Help menu in your NI product. Your NI product will automatically launch the installed version of the documentation in the NI Offline Help Viewer.
5. Optional: In the NI Offline Help Viewer, click Language to change the language.
6. Optional: In the NI Offline Help Viewer, click Navigate » All Manuals to see a list of other documentation sets you can access without connecting to the internet.