Add mcjtylib: https://www.curseforge.com/minecraft/mc-mods/mcjtylib
and rftools: https://www.curseforge.com/minecraft/mc-mods/rftools-base
If there are still issues, also make a test without Rubidium
I am not sure, but the JAVA_HOME part is not working that way - you have to use the full path
Reinstall Java 8 and use the default path - then use
"C:\Program Files\Java\jre1.8.0_391\bin\javaw.exe"
Use a Custom Launcher like FTB App, MultiMC or AT Launcher
With these you can install pre-configured modpacks like All in one: Create or Create and Guns
Did you try these drivers?
https://www.amd.com/de/support/apu/amd-ryzen-processors/amd-ryzen-5-mobile-processors-radeon-graphics/amd-ryzen-5-5600h
Also make sure Java is set to High-Performance mode
https://windowsreport.com/minecraft-not-using-gpu/