Trying to make a dropdown menu dynamically display the next few dates

Site URL: https://www.unit-12.org/food-pantry-signup-1

As part of my job, I've been asked to simplify the application form for my organizations food pantry.

Specifically, my boss wants me to replace the form where you choose a specific time to come collect your food at the pantry with a simple dropdown menu displaying the days in the week with their corresponding dates so customers can feel free to come any time during their chosen day.

Here is the original form
https://www.unit-12.org/community-food-pantry

This service is only available to those living in Hampshire, so I also realised I need to remove or simplify some fields from the form which I found is impossible in Squarespace, especialy the Address form and I can't turn the phone number field into one single entrybox instead of four segmented ones.

I'm still training myself in web design so, as far as I know, the best way to do this seems to be creating a new form from scratch - which I done so far.
https://pastebin.com/E6hS7kwG

Now here's the tricky part.
I previously asked around for help with how to make a dropdown menu work the way I want and what I got so far is this...
https://pastebin.com/VsrjZmUx

I added this to the pages Advanced section, injecting it to the header code but I only found an empty dropdown menu.

So I tried adding the script to the footer code in the Advanced > Code Injection settings page along with a jQuery script tag... Nothing worked.

So what am I doing wrong?

Any help would be much appreciated.
Thanks. Edited January 20, 2022 by bluBerryPi
I originally tried posting examples of my working code but this post isn't displaying it properly, even with the <code> tags! So I'm opting for pastebin links.