First steps

The first things you need to do before you start working with the module
First, decide whether you will use the Unity game client to process requests (case 1) or whether they should be executed on your web server side (case 2).
Case 1
Case 2
Make a trigger that will call the Mysql set config instruction for the Mysql Server, then use the Mysql connect instruction that will connect to your database.
Make a trigger that will call the Mysql remote server file instruction and check Use remote Server File checkbox. Paste Server file Url to which all request will be sent. You can copy this file to your web server from Assets\rezus13\MySql\ folder and write connection settings of your Mysql server in that file.
After that you can use any instruction of Mysql for Game Creator 2 module.