Could not Access File $libdir/vector No Such File or Directory

I am not a DBA. I am trying to test and experiment. I am on a Windows 11 machine and using PgAdmin. I have PostgreSQL 15 installed. When I run CREATE EXTENSION VECTOR, I get the following error message: Could not access file "$libdir/vector": No such file or directory How can I find out where "$libdir" is pointing to? **Edit #1:** Here is what I used to install PGVector: https://github.com/pgvector/pgvector#windows **Edit # 2:** Based on comments below, I thought $libdir was being set by PGRoot, but when I added a vector directory to C:\Program Files\PostgreSQL\15 directory, the same error message came up.