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.