Solution
The NI PXI(e) Embedded Controllers are not shipped with default username and password. With that, either a local account should be created or the user's Microsoft account should be used. In case username and password are requested, it may be possible that someone else configured login credentials for the system. This can be consulted with either IT department of the company or the person who has provided the PXI(e) hardware.
In case the user has lost the password, they can either try a blank password field for the "Administrator" username, which is not guaranteed to work, or follow Microsoft's recommendation for this case, which is the reinstallation of the Operating System (OS). It is possible to restore the operating system on a NI PXI(e) controller using the built-in Acronis True Image or Phoenix Firstware. In case neither Acronis nor Phoenix Firstware recovery work, the restore of the OS can be done using the recovery media that was shipped with the PXI(e) controller.
Neither NI has any tools that would allow the circumvention of entering the user password nor there is a method supported by Microsoft for logging into a Windows system for which the user has lost the password.