For a bit of clarification, since I’m unsure of your experience here…
The translation “file” is a .7z file, openable with 7zip or winrar or some other archiving program. Opening the file will present you with a folder. Copy everything from the folder to your Kanon’s install location (where reallive.exe is) replacing any files.
This comes in the form of a folder named “all ages” that contains a series of files. Copy the files from this folder into your Kanon’s install location.
After you’re done with the translation patch you can choose to download voices for the game. Natively it doesn’t include any voices, so you must download patches for it.
The original voice patch was linked within NDT’s readme.txt, but the downloads have all been removed from the internet over the years. You can probably find it with some googling. The main problem is, even if you do find it, it might be a broken version. I know several Kazamatsuri members have ended up with missing voices throughout the VN.
Alternatively, I have a voice patch you can download that adds some bonus voices, is all-ages out of the box, and I believe it’s quicker to download, so that’s a plus. I can’t guarantee it’s 100% bug free, and it removes the feature to rename the protagonist, but to toot my own horn, it’s easier to obtain and more reliable.
Either way, it’s worth getting a voice patch so long as you have good enough internet to download one. They add a lot to the game, and there’s some stellar performances.