two problems and solutions:

(1) Ryzen doesn't have integrated gpu. although Asus X370 motherboards have. Maybe for the future AMD CPUs.
It needs an external graphic card.

(2) Installing Ubuntu, ACPI error occured. The solution is adding Linux command in UEFI "acpi=off":
- press shift when booting up to get the Grup menu
- move to the ubuntu
- press e
- move to the linux command
- press end
- add acpi=off
- ctrl-x