find_package(OpenSSL) does not search
<OPENSSL_ROOT_DIR>/lib64 for the OpenSSL libs. Is there a reason for that?
OpenSSL 3 in Ubuntu 16 LTS has default lib directory name
I know of two ways to get around this.
The first is set PKG_CONFIG_PATH like
PKG_CONFIG_PATH=<OPENSSL_ROOT_DIR>/lib64/pkgconfig cmake ...
The second is build OpenSSL with