After setting up my Notepad++ to use the proxy settings, I was able to install the DSpellCheck plugin. However, I wasn't able to download the language dictionary files. Despite using different options under the Connection settings dialog of DSpellCheck, it still crashes Notepad++. So, I gave up and install the language dictionary files manually. In this tutorial, I will show you how to manually install the language files.

1. Go to https://github.com/LibreOffice/dictionaries.
2. Open the language folder you want and download all *.aff and *.dic files to %APPDATA%\Notepad++\plugins\config\Hunspell.
3. Restart Notepad++.
4. For my case, I opened the en folder and used
   • en_AU.aff
   • en_AU.dic
   • en_CA.aff
   • en_CA.dic
   • en_GB.aff
   • en_GB.dic
   • en_US.aff
   • en_US.dic
   • en_ZA.aff
   • en_ZA.dic
   • hyph_en_GB.dic
   • hyph_en_US.dic
5. After you successfully installed the dictionary files, you will see the list of languages like the followings.
   
6. Here is how the auto spell check looks like in action.
   

Reference

• https://github.com/Predelnik/DSpellCheck/issues/62