Can't figure out how to download an embedded PDF

FOR LINUX, COMPLETE AND WORKING

1. Install xdotool, AutoKey
2. In Firefox get Save Screenshot: https://addons.mozilla.org/en-US/firefox/addon/savescreenshot/ Then, in Firefox Shortcuts add Ctrl+1 as a hotkey to capture visible page.
3. Create a script for Autokey in Python, mine is:

import time
import os   
import subprocess

pages = dialog.input_dialog(title='', message='Number of pages:', default='5').data

time.sleep(1)
for k in range(1,int(pages)):
    subprocess.run(["xdotool", "key", "ctrl+1"]) # Plugin's hotkey
    time.sleep(2)
    subprocess.run(["xdotool", "click", "1"]) # Mouseclick
    time.sleep(2)

subprocess.run(["xdotool", "key", "ctrl+1"]) # to screenshot the last one

4. In the bottom of a program, set a hotkey to launch it (I set it to Home).
5. Open OP's page and via Inspect Element find the link to embed. It's https://www.sbcaplanroom.com/preview/2477/12610/200647
6. Press F11, make the whole picture fit.
7. Place mouse pointer over next page button, so it clicks each time.
8. Lauch my Autokey script via Home button.
9. Enter number of pages.
10. See how it does it.
11. Open screenshots directory in XnView, select them. Locate it's BatchConvert tool, in Actions tab select a crop action and adjust it to pages' margins. ACHTUNG The last one should be done differently, you can open it in XnV and crop this one alone.
12. Use any tool to stitch them back together into a PDF. I've used PDF Arranger: https://github.com/pdfarranger/pdfarranger But some user down there said it crashed on 600-something pages document.

Result: https://files.catbox.moe/iivoga.pdf