Adobe has officially reached for Acrobat 11 products, meaning direct links on their main website are often broken or redirected. However, you can still access the installer through their official FTP repository or reputable third-party archives: Official Adobe FTP (Direct Download): PDFFilter64Setup.msi

Adobe PDF iFilter 64 11.0.01 (Note: This link may require legacy browser compatibility)

Some users find success with the Foxit PDF iFilter, which is often cited as being faster and more compatible with modern Windows 11 environments. Key Features and Benefits Adobe PDF iFilter 11 for 64 bit platforms | Community

The is a specialized tool that allows Microsoft search engines—such as Windows Desktop Search, SharePoint, and SQL Server—to "read" and index the text within PDF files on 64-bit systems.

Without this filter, your system may only be able to search for filenames rather than the actual content inside the documents.