Can't get Floorp's submodules, how can I build it?

[ruby-R53]

I'm currently trying to build Floorp from source, however I can't get its required submodules to build. I run git clone https://github.com/Floorp-Projects/Floorp.git followed by git submodule update --init --recursive just as mentioned here but that's what I get when running that 2nd command:

[...]
Cloning into '/usr/local/fpkg/Floorp/floorp/Floorp-private-components'...
Username for 'https://github.com':

On this prompt, I put my username followed by password (or token, rather). However, I get this error repeated once:

remote: Repository not found.
fatal: repository 'https://github.com/floorp-Projects/Floorp-private-components/' not found

And then, when trying to build Floorp, I get this error:

RuntimeError: File "l10n-central/en-US/floorp.ftl" not found in /usr/local/fpkg/Floorp/floorp/browser/locales, /usr/local/fpkg/Floorp/obj-x86_64-pc-linux-gnu/floorp/browser/locales

because it couldn't get that submodule (l10n?).
Is there a way to build Floorp without it, or to get that submodule? Or is it just a temporary issue with the repository and I'm just making noise? (I apologize for it if I really am...)

I'm running Gentoo Linux amd64 by the way.