I use eMule because it had a rare doco I found on this site.

https://docuwiki.net/ (Obviously check it's Creative Commons etc before DLing anything)

But you can just search in app. But I can't work out if it's worth adding servers or they are all linked? Or where to get servers from. Or what it all means. I guess I should read a manual.

(Some search material can be illegal (Not from copyright law). Anyone used to these networks I guess knows this, but if new be careful, you will probably autoshare if you accidentally get it)

If it's the same now as it was back when I last used it (more than 15 years ago), it should have a search box. You search within the app itself, it shows the results and you select the file you want to download. You don't need to use an external service.