The DLL called by PDFium VCL is directly downloaded from https://github.com/bblanchon/pdfium-binaries. 
We regularly download the new version of the DLL, and you can also download updates yourself or compile the DLL from source.

Current DLL version: PDFium 148.0.7734.0

Thanks to the PDFim open-source project for providing a stable and powerful PDF development library 
and pdfium-binaries for providing compilation scripts and precompiled DLLs.

Note: 
You must first use DLLs\CopyDLLs.bat to copy the DLL file to the system directory, 
or manually copy the DLL to the demo program for the demo app to run properly.