From the Full Product Download page, enter "10.0.3.mp19" (including the quotes) in the Search box to see a list of links to the release letter and available release packages.
Alternatively, the release packages can be found in the file navigator by selecting the 'NX' button and then navigating through the directory structure by selecting Product updates > Maintenance-packs > Nx10 > [platform].
Sincerely,
Siemens Product Lifecycle Management Software Inc. Digital Factory Division SFB-NX-8000755 Product Information: