CentOS 7 is dead and all its repos have been withdrawn by RedHat.
Also if you are using Apple Silicon (M1, M2, M3) etc., VirtualBox is buggy.
If you are not using Apple Silicon, then continue with a CentOS 9 image from here.
then what is alternative for apple silicon
You can quickly and easily set up an ubuntu server by installing Multipass.
RedHat clones like CentOS are much harder. You would need VMware Fusion, which is free, but a nightmare to find and download from Broadcomm’s website, including having to set up a user account.