Hey so I managed to compile the whole thing. Might as well share with you guys
1. Grab devKitPro, there's a whole installer for it
2. find devKitARM r45 somewhere and drop it into the devKitPro folder (rename the one inside to something else, we won't need it)
3. download the ctrulib_1.1_mod repo, extract the "ctrulib_1.1_mod-master" folder into the devKitPro folder, and then rename it to just "ctrulib_1.1_mod"
4. get aemstro (it's the first result on Google), download the whole repo and extract it to the devKitPro folder and then rename the folder to "aemstro"
5. follow
@Marcogn 's instructions
5a. set up the Environment
5b. grab the core with `./libretro-fetch.sh pcsx_rearmed`
5c. make the .sh file and put it in the "libretro-super" folder (the folder might be in C:/Users/*name*/)
6. from step 7 in the forwarder repo: in C:\Users\*name*\libretro-super\libretro-pcsx_rearmed, change 'snprintf(Config.Mcd2, sizeof(Config.Mcd2), "%s/%s", dir, CARD2_FILE);' to snprintf(Config.Mcd2, sizeof(Config.Mcd2), "%s/../../%s", dir, CARD2_FILE);
7. compile the core with `./libretro-build-ctr.sh`
8. clone the Retroarch-3DS-Forwarders-PSOne, move the compiled core into the folder (in your C:/Users/*name*/ folder) and rename it to libretro_ctr.a
9. where everyone got stuck, download libctru 1.6.0 and replace the libctru folder in the devKitPro folder
10. make a copy or rename the devKitARM folder you added earlier and name it "devkitARM_r45"
11. compile Retroarch-3DS-Forwarders-PSOne and you should have a .cia
12. extract the .cia with HackingToolkit3DS, rename the files and copy them into the PS1 Forwarders Creator folder under tools/assets_ps1
13. do the rest of the repo's steps
if you need me to go into more detail, I'd be happy to help