Run this frontend app locally. VScode's live server would usually run your frontend on port 5500 i.e. on http://localhost:5500 for other devices apart from iOS. For iOS, use IP address as directed below.
Step 1: Get your IP address
Step 2: In browser on iOS device, go to http://YOUR_IP_ADDRESS_GOES_HERE:5500, to see the app running.
Step 3: In the frontend's helper.js, locate the iOS code below and replace this part of the backend URL YOUR_IP_ADDRESS_GOES_HERE with your IP address.
const response = await fetch(`http://YOUR_IP_ADDRESS_GOES_HERE:4000 ...etc.
Step 4: Visit the Backend repo's readme for instructions on how to ensure successful itunes music fetch on iOS devices.