Grails - How to download zip manually and install using SDKMan

I tried to download the grails using SDKMan with:

 sdk install grails 2.5.4  

but it failed because of slow internet connection.

Then, I went directly to grails.org and downloaded the zip file and added it to /Users/<username>/.sdkman/archives/

To install the plugin, run 

 sdk install grails 2.5.4  

Done!

To see if the plugin is installed,

 sdk list grails