from tkinter import *
from tkinter.ttk import *
import time
from ctypes import windll
windll.shcore.SetProcessDpiAwareness(1)

def start():
    GB = 10
    download = 0
    speed = 1
    while download < GB:
        time.sleep(0.2)
        print(download/GB)
        download += speed
        bar['value'] = download / GB * 100
        percent.set(f"{int((download/GB)*100)}%")
        text.set(f"{download}/{GB} GB downloaded")
        window.update_idletasks()

window = Tk()

percent = StringVar()

percentLabel = Label(textvariable=percent)
percentLabel.pack()

text = StringVar()

taskLabel = Label(textvariable=text)
taskLabel.pack()

bar = Progressbar(window, orient=HORIZONTAL, length=300)
bar.pack(pady=10)

button = Button(window, text="download", command=start).pack()

window.mainloop()