If you use MyDAC to connect to MySQL in Direct mode, you do not need to have MySQL client library on your machine or deploy it with your MyDAC-based application.
If you use MyDAC to connect to MySQL in Client mode, you need to have access to the MySQL client library. In particular, you will need to make sure that the MySQL client library is installed on the machines your MyDAC-based application is deployed to. MySQL client library is libmysql.dll file for Windows, or libmysqlclient.so (libmysqlclient.so.X) for Linux. Please refer to descriptions of LoadLibrary() and dlopen() functions accordingly for detailed information about MySQL client library file location. You may need to deploy the MySQL client library with your application or require that users have it installed.
If you are working with Embedded server, you should have access to Embedded MySQL server library (libmysqld.dll). For more information visit Using Embedded server.