Missing "Display Driver" option in AMD setup

I am an owner of Sapphire Radeon HD 4870 VaporX (DEV-ID 9440) on Windows 10 Pro x64. I have an issue with modded drivers - I can install HDMI audio drivers only, but the option for Display Driver and/or CCC doesn't show up. I assume I'm doing something wrong, so here are the informations:

Drivers I've tried to mod:
18.4.1, but it gave me a lot of .NET(?) errors, so I knew it wouldn't work.
16.2.1 - the latest legacy driver for 5xxx and up
15.7.1 - the latest stable legacy driver for 5xxx and up
Base drivers I've used:
13.9 for Windows 7
13.1 for Windows 8

I've selected the necessary files according to the Guide, ones for OpenCL, *dxx.dll and *cfx.dll from 13.9 or 13.1. FLEM did say, that there were missing strings in C*****.inf file (don't exactly remember how it was with 18.4.1, apart from mentioned errors). Process finished in ~4 seconds. Then I'm trying to install it with the Setup.exe file, but as I said, I don't have the option for Display Driver or CCC.

Could someone tell me, what am I doing wrong?

EDIT: Also, manual installation of modded drivers via Device Manager doesn't go through - "Windows decided, that current drivers are optimal" or something like that, tried with no drivers installed (Basic Microsoft GPU, I don't have Windows in english so I'm translating it on the fly). However, manual installation of 13.9 or 13.1 is working, and I can install CCC from one of those drivers, but it doesn't work - "no options available to configure". I'm attaching my logs, in case that would help.

I've stated already, that manual installation doesn't work, and that modding any driver seem to give me the "missing string" error. The only drivers which I've managed to mod, are 15.11, there are FLEM mods in the *.inf file, but the driver doesn't go through the Device Manager installation process - "Windows has determined that optimal drivers are installed (Basic Display Adapter Driver..)".

14.4 also worked, and I can install the display driver via the setup.exe, but I'm getting the driver error code 52. I have test mode enabled, and disabled system integrity check.

Would you be able to try to mod those drivers remotely, ex. via TeamViewer?

I pointed from there to the *.inf file of modded 15.11 driver. Now I'm getting code 43.

I've used Windows 8 13.1 legacy, as a base, however I'd like to use 13.9 Windows 7 legacy - 13.1 is from November of 2012, 13.9 is from April of 2013 (according to FLEM).

I'll try, give me a few minutes.

Error code 43, again.

I'll be trying now with 13.9 (previously used 13.1). Should I reboot after using DDU? And also, should I download older drivers (like 12.6 or 13.1) for Windows 8, or 7?