Continue and use the single line installer. You will be asked a set of questions during the installation. As you are connecting to SlapOS master, you are supposed to skip the first two questions.
Choose a name for your computer (like SOFTWARE-BOX-1 to identity it in your network and finally enter the association token you have received earlier from your Rapid.Space panel and input ens4 for IPv6 interface (if you are using Rapid.Space KVM).
Once the installation has finished without errors, you should see:
...
PLAY RECAP ************************************************************************************************************************
127.0.0.1 : ok=13 changed=2 unreachable=0 failed=0
Note: In case installation fails and you want to start over, you need to request a new token as mentioned above and, depending on whether already created, remove any existing configuration in /etc/opt/slapos/slapos.cfg
before restarting. For example, while you install SlapOS node in Rapid.Space KVM, you keep the default interface "lo" , you have to remove /etc/opt/slapos/slapos.cfg
before restarting.