In order to set the build type (Debug vs Release), you have to use the CMAKE_BUILD_TYPE variable when invoking cmake like so: cmake -DCMAKE_BUILD_TYPE=Release. The supported types currently are: "Debug" and "Release".
Note that this only works for single-config generators. If you are using a multi-config generator (e.g. visual studio projects), the steps
mentioned above won't have any effect. Instead, you'll have to choose the config type when invoking the build itself. This works by using e.g. cmake --build . --config Release.
If the automatic search process of cmake doesn't result in the proper version of OpenSSL being selected (e.g. an older/incompatible system version
could be chosen over the manually installed one), you always have the option of explicitly telling cmake where to look for OpenSSL via the
OPENSSL_ROOT_DIR option.
If for instance you have installed OpenSSL to /usr/local/opt/openssl, you can invoke cmake like this:
cmake -DOPENSSL_ROOT_DIR=/usr/local/opt/openssl ..