Faq/General/Defender Controlled folder access
Installing LibreOffice on Windows with Defender Controlled folder access feature enabled
This applies to Windows 10 Fall Creators update (1709) and later.
Due to the interference of the Defender Controlled folder access feature with LibreOffice installation process, it is required to disable this feature for the duration of installation process. Failing to do that may cause errors 1336, 2902, warning 1909, and failed installation.
For details on how to disable and re-enable the feature, refer to this Microsoft knowledge base article.