Can't run code in Keil for STM32L433RCT6P on NUCLEO-L433RC-P
Device not found in available Device Family Packs.
  Use PackInstaller: 'Check For Updates' to update the list of supported devices.


Keil doesn't know the device. Since Keil 5, it doesn't by default come with all supported devices. You have to install devices manually via the Pack Installer.



In the log:


  No Algorithm found for: 08000000H - 08000F53H.


Since Keil does not know the device, it has no idea how it should even begin to program it. It needs firmware to load in SRAM and run to be able to program flash. This comes with the pack installer.




  Error:  Flash Download failed - "Cortex-M4" 


That's just the least descriptive error message you get on almost every error.
Get used to it.