Is there any quickstart for installing tiller and helm charts?

Hi, I’m trying to migrate from Rancher 1.6 and I’m new to Kubernetes so please forgive me if my questions are too basic. I hope my questions and answers to this tread will be useful for others with similar problems too.

I installed Rancher 2.1 cluster correctly (all nodes are green) but instructions on ready to use apps (helm charts) doesn’t seem to work, Tiller is kinda installed but I think there is some problem with namespaces/RBAC.
I’m not sure if this is lack of my experience with k8s or RKE is somewhat different than “clear” k8s.

I think it would be great to write some small page in docs to let know beginners like me how to start and take advantage of already done docs of other projects. So far it’s very complex to understand versus Cattle which I really liked and it got job done much faster with smaller learning curve.

My first steps with MySQL on Rancher

For almost all my apps I need MySQL or similar so I began with percona which I found as the first

$ helm install --name kubeconf stable/percona
Error: release kubeconf failed: namespaces "default" is forbidden: User "system:serviceaccount:kube-system:default" cannot get namespaces in the namespace "default"

No dice and I don’t even know what to put in search engine. When I search for:

rancher rbac tiller

First link - Rancher v1.6 docs:
It’s still for me as a v2.1 user or it’s outdated?