Inorder to port a game to iOS you must pay Apple $99 Per Year to upload the application to the Appstore.
You also need to be on a Mac to even build the application for iOS as it's not possible to do it from a PC.
It's also very likely that this would not survive on the Appstore because it's a mod of baldi's basics classic and baldi's basics classic is on the Appstore.
Now there's a workaround if your device is jailbroken but I don't recommend it for security reasons and also it's a legal grey area.
(EDIT: Also according to other comments I've read Balderfuge DX's input system is different than Subterbaldi's input system and apparently harder to make mobile controls for.)