Let's say something like this is being returned.

FATA[0000] rpc error: code = Unauthenticated desc = error while validating and normalizing app:
error validating the repo:
error getting k8s server version:
the server has asked for the client to provide credentials

I got this when attempting to create an app.

argocd app create demo \
--repo https://github.com/my_project/my_repo.git \
--path python \
--dest-namespace my_project \
--dest-server https://api.dev.openshift.example.com:6443

As the error suggests, this has something to do with credentials. I would start by checking to see if the STATUS of the cluster you are targeting is "Successful" or Unknown. If Unknown, then the credentials issue may have been when attempting to add the Kubernetes or OpenShift cluster to ArgoCD.

~]$ argocd cluster list --grpc-web

SERVER                                       NAME                VERSION    STATUS      MESSAGE                                                  PROJECT
https://api.dev.openshift.example.com:6443   dev-cluster                    Unknown     Cluster has no applications and is not being monitored.
https://kubernetes.default.svc               in-cluster          1.27       Successful

Check out my article Add Cluster using the CLI for more details on add a Cluster to ArgoCD.