How to download and install mysqlx plugin into MySQL?

Question

I would like to use mysqlx/xdevapi.h in C++ and for this must be installed MySQL X Plugin in MySQL.

I tried:

mysql> INSTALL PLUGIN mysqlx SONAME 'mysqlx.so';

I got this message :

ERROR 1126 (HY000): Can't open shared library '/Applications/MAMP/Library/lib/plugin/mysqlx.so' (errno: 2 dlopen(/Applications/MAMP/Library/lib/plugin/mysqlx.so, 2): image not found)

He's right, the plugin isn't really there. As you can see I am using MAMP on MAC OS.

Info about DB server:

Server: Localhost via UNIX socket
Server type: MySQL
Server connection: SSL is not being used Documentation
Server version: 5.7.26 - MySQL Community Server (GPL)
Protocol version: 10
User: root@localhost
Server charset: UTF-8 Unicode (utf8)

Is there a page where to download the plugin? Thank you for help!