Please write your question in detail here.
(Environment) Implementation pc: Mac Mac version: Mac Mojave 10.14.5
Installed CentOS version: http://ftp.iij.ad.jp/pub/linux/centos/8.0.1905/isos/x86_64/CentOS-8-x86_64-1905-dvd1.iso
(Purpose) I want to install centOS on VirtualBox.
(Current status) Executed until after pressing the restart button based on the following site.
Citation site https://www.hitoriit.com/entry/2019/09/28/180000

Error message

(Problem) It seems that such a startup screen appears on the site, but on my screen, the first screen appears.