Appropriate python web framework for my custom interface

I'm a newbie in python dev... so be gentle :)

I wrote a script in python with the following syntax structure:

def #....

def #...

def #...

def Main():
   #Enter username
   #Enter password
   #Program body
   #Save file to specified location

if __name__ == '__main__':
   Main()

I want to build a minimalist and straightforward python web framework that does the following:

1. Has two url routes:

   a. Homepage to ask for the password and username, supplied to the main body of the python script

   b. Next page to ask for file location to save results.

I need assistance on:

Suggestions on frameworks that can achieve my objective:

Please support your answer with a practical example on how the framework will call the python script I've written above after the I've supplied the correct username, password and results location.

I've looked at a couple of web frameworks like: Django: Steep learning curve Flask: Not minimal enough for my needs