This tool in Acrobat Pro allows you to define a group of PDFs as a "catalog" and create a unified index for the entire collection.
Before indexing, use File > Info > Properties to add titles, authors, and keywords. This makes your index even more powerful during advanced searches.
Then she remembered: .
If you are searching for "index of acrobat pro" because you need a specific resource, there is almost always a safer, official route.