To communicate with client systems, HTTPD needs to be able to communicate on TCP ports 80 (HTTP) and 443 (HTTPS). Run the commands

# firewall-cmd --zone=public --add-service=http --permanent
success
# firewall-cmd --zone=public --add-service=https --permanent
success
# firewall-cmd --reload
success
#  

on casdev-casapp and casdev-samlsp to open these ports in the system firewall.