I apologize for the confusion. Since the PicoCalc platform is not officially supported by PicoMite (and likely never will be), and since Clockwork originally just released a (somewhat broken) port of a really old version of PicoMite when the device was released, I decided to try to port the newest version. The version numbers in my repo (which you linked above) originally tracked with releases of the official PicoMite and WebMite. There were a few extra “in between” builds that I just added an “_a”, “_b”, “_c” to if necessary. But then the official version released a final V6.00.02. It was unclear what I should call additional PicoCalc releases after that point, so I added the clunky: “_PicoCalc_RC1” and eventually hope to settle on a “_PicoCalc_Final”
All of this is made difficult by the fact that the official releases are just made available whenever they are made available, with little to no warning, and then the forums here start clamoring for a release to match. If you’re interested in a look at the history and the mess it’s all been, check this post.
Since you’ve got a Pico W, unfortunately the only option you have, if intending to use MMBasic, is PicoMite_PICO_V6.00.02_PicoCalc_RC1.uf2. WebMite is only supported on Pico 2W (not Pico W), and that’s a decision made by the official maintainer, and not something that I’d be able to work around. It depends on code that only runs on a RP2350 (Pico 2 or 2W). If you’d like to use the wireless functionality of your Pico W, then you’ll need to consider using MicroPython, the Arduino platform, or any of the other growing number of options that are available (like FORTH, uLisp, etc.)
Sorry for the cryptic release filenames, but I was using the build targets as defined by the official project. I realized later that they aren’t really all that helpful for folks who aren’t thinking about the processor in their module. They are described in this older release.
But the TL;DR is:
If you have a Pico or Pico W, you can only install a release with a name like:
PicoMite_PICO_V6.00.xxxxx.uf2
(and you won’t be able to use wireless functionality since it won’t be WebMite)
If you have a Pico 2, you can only install a release with a name like:
PicoMite_PICORP2350_V6.00.xxxxx.uf2
(and you won’t be able to use wireless functionality since it won’t be WebMite)
If you have a Pico 2W, you can install either
PicoMite_PICORP2350_V6.00.xxxxx.uf2
(and you won’t be able to use wireless functionality since it won’t be WebMite)
or
WebMite_WEBRP2350_V6.00.xxxxx.uf2
(and you won’t be able to overclock as high because WebMite limits this due to instability)
Some of the older releases also had .bin files. There’s an ongoing project to load firmware dynamically from the SD, and those were built with that in mind. That project is still being worked on and I hope to eventually support it so we don’t haev to worry about flashing firmware the normal way anymore, and will only have to flash the bootloader firmware once and then load everything else direct fromt he SD. But it’s not completely ready yet (at least for PicoMite/WebMite), so we’re using what we’ve got. 
Also worth noting, I’m just another customer of ClockworkPi and provided these builds because they weren’t really making a clean source fork from the official version available, and after the apparent drama it was clear the official version would likely never support the PicoCalc anyway. I wanted one, gave it a shot, and figured it might be useful to others. It’s unfortunate that Clockwork doesn’t indicate what modules work with what software, but that’s just how it is, I guess. They make good hardware, but software has never been their focus or strength.