setp 1:

download url:http://mirrors.huaweicloud.com/centos-altarch/7.8.2003/isos/armhfp/CentOS-Userland-7-armv7hl-RaspberryPI-Minimal-4-2003-sda.raw.xz

other url:http://isoredirect.centos.org/altarch/7/isos/armhfp

setp 2:

flash to you TF-Card

you can use balenaEtcher by url:https://www.balena.io/etcher/

setp 3:

flash to you TF-Card

setp 4:

 update system

sudo yum update

end.