If you do not have the required libraries and headers installed, then the server will still build, but many EAP types will not work. The server will print out error messages in debugging mode, such as:
If PEAP or TTLS do not work for you, then run the server in debugging mode, and look for an error like the one quoted above. If you see a similar error, then you will need to re-build the server with OpenSSL support.
If PEAP or TTLS do not work for you, and the above error does not appear, then something else is wrong. The usual suspects are the server certificate (see the EAP problems page), or the user's password is incorrect.