@Ben-Nash
Some years ago the TextFX plugin was part of all Notepad++ installations. This has changed somewhere in the past. Now you have to install it separately via PluginsAdmin, the new build-in plugin management system of Notepad++ since v7.6.
Note: Do not use the old PluginManager anymore, it is not suitable for recent versions of Notepad++ !!.
Though there is also a 64 bit version of TextFX you should not use it, it isn’t working reliable. Take the 32 bit version instead. Thus you have to install a 32 bit version of Notepad++ as well.
But you should use the latest version of Notepad++ which is v7.7.1. You can download it at the project’s website.