How do I find the openssl libraries on Linux (Debian buster)

Debian (or GNU/Linux system in general) don't use .dll files for OpenSSL. There are no such files as libeay32.dll and ssleay32.dll. On Debian Buster you can find OpenSSL shared libraries libcrypto.co.1.1 and libssl.so.1.1 in /usr/lib/x86_64-linux-gnu/ (depending on your CPU architecture).