Microsoft has announced that they are no longer offering offline symbol packages as a downloadable MSI. For those who need to download symbols to debug their applications or Windows, you will now need to connect directly to their symbol server or use the symchk utility to download them. Microsoft has made significant improvements to the online Microsoft Symbol Server by moving this to be an Azure-based symbol store, and symbols for all Windows versions and updates are available there. If you do not wish to connect to the symbol server, you can instead use the Symchk tool to download any necessary PDB files.
Source: https://www.bleepingcomputer.com/news/microsoft/microsoft-is-no-longer-providing-offline-msi-symbol-packages/