According to the Linkerd page, it says that I need to generate my own mTLS root certificates by running the following command:

Where do I run this command? I’ve looked at the instructions, but it remains unclear.

My Rancher server infra: L4 load balancer, RKE workstation, and my Rancher Server node.

My cluster (that I created using Rancher) infra: 1 control plane, 1 worker node.

I’m using Rancher’s Apps->Chart section and then looking for Linkerd.

If you follow the CLI instructions in the official linkerd docs, you wouldn't need to install it through the Rancher UI. However, if you wanted to manipulate the cluster with helm from your local workstation as described in the doc, you would need to go to the Rancher UI just to grab the kubeconfig from the top nav of cluster explorer and place it locally. Then you can use that to interact with the cluster with kubectl and helm. If you went through the rancher UI route, you would use the step command to generate the certs locally, then I think you would insert the certs into the form as you install the linkerd chart through Apps & Marketplace.