K3s cluster migrate between rancher installations

Hi!
I had an older 2.5 Rancher deployement (running on a k3s cluster) that was managing another imported k3s cluster.
The Rancher installation went into some weird issues one day and I could not get it working again.

The k3s cluster which it was managing, however, is fine, I can access it directly and use it.
I created a new Rancher 2.5.8 deployment and I would like to import the k3s cluster on it.
Are there some recomended ways to do that? Do I just import it into the new Rancher UI?

Thanks!

So I just imported the old k3s cluster into the new Rancher installation.
I can see it in Rancher, download the kubeconfig file and use it for kubectl access.
But I don’t see any of the existing namespaces in the default project. They were created previously from Rancher and were assigned to the default project.
Is there a way to import the existing namespaces in the Rancher project?

Thanks!