You should run all those commands on any of the members, NOT the deployer as you will get the error you are getting. All these commands run from the members (remember the captain does alot of the work here) and NOT the deployer:
splunk show shcluster-status
splunk list shcluster-members
splunk list shcluster-config
splunk rolling-restart shcluster-members
To make sure that you have the SHC members pointing to the right Deployer, run the command:
./bin/splunk list shcluster-config -auth username:password
Once you see the members are pointing to the right Deployer, that means you have set up and ready to push. simply place your untarred apps under /shcluster/apps and push with: splunk apply shcluster-bundle -target https://oneOfmySHs:8089
Check the apps have been deployed to /etc/apps folder on the members and run splunk rolling-restart shcluster-members on any peer if they have been downloaded by the peers and not taken affect. I.e when forwarding internal logs to idx layer, the SHC members might recieve app from the deployer but not implement, in that case, kick off a rolling restart.
I hope this helped, i have struggled with similar issues in the past wtih SHCs.
you are getting this because you are running the right command on the wrong node. deployer just pushes the app on search head nodes , SHC master is one of the search head node, so try to run the command from one of the search head node and it would show up the cluster info if SHC is configured correctly.