Help! How can I unpack/unzip/decode a "game.arcd" file?

Hi I'm trying to mine textures from a game that's apparently built using the Defold game engine and can't seem to find a tool that actually opens this group of files.

I found this blog post where someone talks about how the files 'work' but it doesn't help me because their tool failed for me.

game.arcd
Game archive file containing the actual data

game.arci
Game archive index file containing the data offsets

game.dmanifest
Manifest file containing the file names

Click to expand...

So far I've tried these tools and none of them have worked for me:

• Codeberg - arcdEx: .arcd file extraction tool (from blog guy, didn't work)
• GitHub - JustAPotota/Unfold: Defold modding tool (didn't work)
• GitHub - wattostudios/GameExtractor: Edit game image archives. (seems like it might work but costs $10 and I'm skeptical)

Any advice would be appreciated!