How to use window_create method in customtkinter

I'm trying to build a chat system like a normal messenger interface using customtkinter, but I'm having attribute error.

    self.chat_frame = ct.CTkFrame(self)
    self.textbox = ct.CTkTextbox(self.chat_frame, width=400, height=400)
    self.textbox.grid(row=0, column=0, padx=(10, 0), pady=(10, 0), sticky="nsew")
    self.entry = ct.CTkEntry(self.chat_frame, placeholder_text="Hi there! I'm Bella, let's chat")
    self.entry.grid(row=3, column=0, padx=(10, 5), pady=(20, 20), sticky="nsew")
    self.chat_button = ct.CTkButton(self.chat_frame, width=10, text="Send", command=self.on_submit)
    self.chat_button.grid(row=3, column=2, padx=(0, 10), pady=(20, 20))
    self.entry.bind("<Return>", self.on_submit)

    def on_submit(self, event=None):
        wrap = self.entry.get().strip()
        user_input = textwrap.fill(wrap, 30)
        self.entry.delete(0, 'end')
        if user_input != '':
            self.textbox.configure(state='normal')
            self.textbox.insert(tkinter.END, current_time + '', ('small', 'right', 'greycolour')),
            self.textbox.window_create('end', window=ct.CTkLabel(self.textbox, fg_color='#000000',
                          text=user_input, wraplength=200, font=('Arial', 10), 
                          bg_color='lightblue', justify='left'))
            self.textbox.insert(tkinter.END, 'User '+'\n', 'left')
            self.textbox.yview(tkinter.END)
            self.textbox.configure(state='disabled')

Using Python 3.

source https://stackoverflow.com/questions/75839227/how-to-use-window-create-method-in-customtkinter