The DTSXMP RPM is not available in apollon Spacewalk. You can download the RPM here: dtsxmp-3.1.1-15.el9.x86_64.rpm

Copy the RPM to the target system

scp dtsxmp-3.1.1-15.el9.x86_66.rpm root@target-system.pd.apollon.de:/root/

Establish a connection to the target system

ssh root@target-system.pd.apollon.de

Install the DTSXMP RPM

cd /root

yum install dtsxmp-3.1.1-15.el9.x86_64.rpm