Yes, it's possible to use DocSearch for PDF documents.
You can use “URL Tester” in the crawler.algolia.com dashboard to test out PDFs you'll be crawling. Here is a guide, and an example of what the config looks like.
The free DocSearch plan, doesn't include technical web support from the Support team. For further assistance, you can post your question on the Algolia Community Forum or Discord. For front-end issues, you can raise the issue directly on GitHub. In addition, you can review our DocSearch Documentation and FAQ.