Problem with find_package(MySQL) and cmake

I have built Mariadb connector and then tried to build drogon from head passing -DBUILD_MYSQL=ON in cmake command line. MySQL_ROOT environment variable is pointing to Mariadb installation location and yet find_package(MySQL) fails in drogon. I can't figure out what is wrong.
Update:
I was able to set environment variables:
export CMAKE_INCLUDE_PATH=$MySQL_ROOT/include/mariadb:$CMAKE_INCLUDE_PATH
export CMAKE_LIBRARY_PATH=$MySQL_ROOT/lib/mariadb:$CMAKE_LIBRARY_PATH

to have FinMySQL.cmake work with mariadb (I guess the subdirectory mariadb under include and lib makes this a requirement), but I next encountered another error:
None of the example clients would link properly as mariadb was built with libzstd and I guess drogon doesn't link with libzstd. So the workaround was to remove libzstd from mariadb module and then use that module to build drogon examples.