First of all, thanks for the help.That's your problem right there. You either don't have the compiler installed, or you don't have your PATH variable configured properly.
I don't think I understood the core of the problem, but I can say that all the downloads mentioned in the instructions have been completed successfully. I checked, and the only warning I got was this:
warning: config file /etc/pacman.conf, line 89: directive '[dkp-libs]' in section 'dkp-windows' not recognized.
warning: config file /etc/pacman.conf, line 90: directive '~' in section 'dkp-windows' not recognized.
error: could not register 'dkp-libs' database (database already registered)
error: could not register 'dkp-libs' database (database already registered)
error: could not register 'dkp-windows' database (database already registered)
warning: config file /etc/pacman.conf, line 90: directive '~' in section 'dkp-windows' not recognized.
error: could not register 'dkp-libs' database (database already registered)
error: could not register 'dkp-libs' database (database already registered)
error: could not register 'dkp-windows' database (database already registered)
After the command: pacman -S 3ds-dev git make python3 mingw-w64-x86_64-gcc unzip --noconfirm .
I then downloaded a git: wget https://github.com/3DSGuy/Project_CTR/releases/download/makerom-v0.17/makerom-v0.17-win_x86_64.zip
And unzipped it. I then set some paths.
export PATH="$PATH:/opt/devkitpro/tools/bin"
export DEVKITPRO=/opt/devkitpro
export DEVKITARM=/opt/devkitpro/devkitARM
export DEVKITPPC=/opt/devkitpro/devkitPPC
I then downloaded the git of sm64-port (git clone https://github.com/mkst/sm64-port.git). I changed the current directory to C:\msys64\home\HP\sm64-port and then tried running these* two commands in order to extract the assets from the rom (hash: d80ee9eeb6454d53a96ceb6ed0aca3ffde04509, that is US). At this point I should have everything, right? Makerom is there (in the bin folder of MSYS, so it can be executed), maybe it's gcc that's causing problems? (And surely the fact that i don't know what gcc is doesn't help ... )export DEVKITPRO=/opt/devkitpro
export DEVKITARM=/opt/devkitpro/devkitARM
export DEVKITPPC=/opt/devkitpro/devkitPPC
*The commands in question, in case they're needed:
cp /c/temp/baserom.us.z64 ./ --> Here I copy the rom I placed in a temp folder into the current directory.
make VERSION=us cia --> Here I make the .cia file, and here comes the error.
I tried describing everything I did in details, hopefully I was clear about the situation. Thanks again for answering, i'ts really appreciated!