By default, Envision will embed the PDFium DLL directly in the resulting compiled EXE.

See the section in the help file, 

User's Guide | External or embedded DLL's?

for more information.

https://github.com/bblanchon/pdfium-binaries


NOTE: If you are still targetting Windows XP or Windows Server 2003, you need to use 
older versions. See the xp subfolders. You must include the XP specific DLL in the same 
folder as your EXE, and it will automatically load it. 

The XP DLLs are old and will have more problems rendering some PDFs than the latests PDFium DLLs. Use them if you absolutely need to use them.

The original XP compatible DLLs are here,

https://github.com/pvginkel/PdfiumViewer/tree/d567bc3cbbd012db7ba294bfa17cffdb82e8a717/Libraries/Pdfium/Windows%20XP%20compatible