Update 2. I built a K3s cluster on 1.22 - I did duplicate the primer.sh error "Cluster is not CSI ready". However, I believe this to be a cosmetic issue with our primer script that we will have to look in to further. I suggest testing with kubestr as this validated on my cluster. I'll paste here my entire set of notes for setting up my 1.22 K3s cluster with longhorn and Kasten.

Prepare K3s Nodes for Longhorn ISCSI (CentOS 7)
--------------------------------
yum install -y iscsi-initiator-utils

cat <<EOF > iscsid.te
module iscsid 1.0;
require {
        type iscsid_t;
        class system module_load;
}
allow iscsid_t self:system module_load;
EOF
checkmodule -M -m -o iscsid.mod iscsid.te
semodule_package -m iscsid.mod -o iscsid.pp
semodule -i iscsid.pp
rm -f iscsid.mod iscsid.te iscsid.pp

(Install Longhorn from Rancher UI)

Install snaphot CRDs
------------------------------------
git clone <https://github.com/kubernetes-csi/external-snapshotter.git>
kubectl kustomize external-snapshotter/client/config/crd | kubectl create -f -
kubectl -n kube-system kustomize external-snapshotter/deploy/kubernetes/snapshot-controller | kubectl create -f -

Enable Longhorn Snapshot Class
--------------------------------------

cat <<EOF>> longhorn-csi-snapshotclass.yaml
apiVersion: <http://snapshot.storage.k8s.io/v1|snapshot.storage.k8s.io/v1>
kind: VolumeSnapshotClass
metadata:
  name: longhorn
  annotations:
    <http://k10.kasten.io/is-snapshot-class|k10.kasten.io/is-snapshot-class>: "true"
driver: <http://driver.longhorn.io|driver.longhorn.io>
deletionPolicy: Delete
EOF
kubectl apply -f longhorn-csi-snapshotclass.yaml --kubeconfig k3sconfig

Install local minio for longhorn
--------------------------------------
kubectl create -f <https://raw.githubusercontent.com/longhorn/longhorn/master/deploy/backupstores/minio-backupstore.yaml>

Go to the Longhorn UI. In the top navigation bar, click Settings. In the Backup section, set Backup Target to

<s3://backupbucket@us-east-1/>

And set Backup Target Credential Secret to:

minio-secret

Testing CSI
---------------------------------------
kubestr csicheck -s longhorn -v longhorn

Install Kasten K10
----------------------------------------
helm repo add kasten <https://charts.kasten.io/>
helm repo update
kubectl create namespace kasten-io
helm install k10 kasten/k10 --namespace=kasten-io

Port Forwarding Kasten UI
---------------------------------------
kubectl --namespace kasten-io port-forward service/gateway --address 172.18.117.110 8080:8000 > /dev/null 2>&1 & 

Demo Application (Pacman)
---------------------------------
kubectl create namespace pacman
helm repo add veducate <https://saintdle.github.io/helm-charts/>
helm install pacman veducate/pacman -n pacman

well, fired up a scaleway machine, just follow your runbook (ubuntu, not centos), and snapshoting not working on v1.21 k3s :

Job failed to be executed Failed to fetch the snapshot session Volume Snapshots are not supported for this storage provider.Try K10's Generic Storage Backup method(https://docs.kasten.io/latest/install/generic.html?#generic-storage-backup-and-restore) or contact support@kasten.io

which is pretty the same as k10 prerequisites tool