I can try and give you some additional hints... so this is Buerakus original description to how to install his mod:
1) You need to download and install 7z Archiver and Asar plugin for it.
2) Extract mod's archive into HRT root folder.
3) Open resources/app.asar via 7z archiver and replace index.html with index.html that comes with mod.
4) Run the game and type "klib" into console to check if it's installed and get mod menu ability.
here are my additional hints:
1) you need the "Asars pluglin" so your 7z tool can extract and pack .asar files. Without these addditional plugin it will not work.
2) i think this instruction is clear, right? Just unzip the whole mod into your HRT root folder (were you find the "HeroineRescueTeam.exe" file). This will create some additional folder/files, e.g. ../data/klib and also ../resources/klib_assets
3) At this point i made an error. I first unpacked the app.asar file and than tried to put the index.html and than pack the app again.
That is wrong! You must not unpack the app.asar file. Just add the index.html file into the existing app.asar archiv without unzipping the app.asar file (that should be possible if you have the plugin).
4) ... again that should be clear, right?
I hope that helps. If not, the modder (Buerakus) is available at Enlit3d discord and i am sure he can give you better support