I don't have one of the affected device, and I don't recall the details, but, no, manual intervention *might* be needed to get the final FW update. Check what you're running in the Device Info section of the Help menu on the device.
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That aside, the obvious issue is what's happening with archives. Some of it may be on you, some of it may be on your OS, some of it may be on the program (if any) you're using to unpack archives.
For things to go as planned:
*.tar* files should stay completely untouched, and dropped as-is in the right place.
*.zip files should be uncompressed *directly* to the right place, *without* creating a top-level folder (by "directly", I mean what's usually the "Extract To" option of an unarchiving app, instead of unpacking it somewhere, and moving that manually. And creating a top-level folder named after the archive is often the default behavior of an unarchiver for archives which contains multiple top-level entries, which is the case here).
Getting all of that to behave in a consistent manner can sometimes be tricky, and what we need is often not the default behavior of an OS/unarchiver. And taking care of that is fairly hard to detail in a "one-size fits all" manner.
Hence the install scripts for the semi-auto packages

.
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GitHub releases are packaged to be unpacked to the .adds folder, a folder you *may* have to create yourself in some cases (the wiki instructions *should* be ordered in a manner that should ensure it'll already have been created by something else first, though

).
And yes, you're meant to use a Kobo binary package. The unnamed zip link on the bottom is the source-code, which won't do you any good in this context

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The semi-automated packages are designed to be unpacked to the root of the device. Or, better yet, to let the install scripts handle it.
Speaking of that, since you mentioned KSM in relation to that, and it has come up before: was your confusion stemming from the Wiki page, or the MR thread?
To be clear: these do *NOT* have anything to do with KSM. They don't use KSM, they don't need KSM, they won't install KSM, and they won't do anything (much) if you're already using KSM

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I'm probably being a bit too verbose, when in fact things should be as simple as "unpack the right file the right way in the right folder"

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There's just a few potential interactions one might not be aware of that can gum up the works

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That was one of the things that drove me to create the install scripts, and why I'm always careful about install documentation, because this isn't a new issue, in fact, over the last 8 years of so of maintaining custom stuff for eReaders, it's probably a source of confusion for a good third of the support requests we get

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