follow the whole video and it should work (at least if you run checkra1n jailbreak and ios 12.5.7 because that’s what i used in this video)
Other IOS versions might differ slightly in how you make it work but it shouldn’t be that big of a difference that you’ll have to go searching for hours on google to make it work. The basic tweaks should be the same
*If Lowerinstall doesn’t show up in your settings then go to the link below and install preferenceloader. that should get lowerinstall visible and you can then change the ios version and device code (use something real like Iphone14,4 and IOS 16.1.1 – Simulating an iphone 13 mini)