Hello Fajar -
Download links are available here:
Since you are using RabbitMQ 3.7.12, use this zip file:
Delete the git repository that you have extracted on your machine, then un-zip the contents of the rabbitmq_delayed_message_exchange-20171201-3.7.x.zip file into this directory:
C:\Program Files\RabbitMQ\rabbitmq_server-3.7.12\plugins
From the Start menu, open the "RabbitMQ Command Prompt (sbin dir)" item, and run this command:
.\rabbitmq-plugins.bat list
You should see the new plugin included in the list, and you can then enable it.
Thank you -
Luke