Install vault injector in openshift

We have vault externally hosted. I need to connect to this from openshift.
To install just the vault agent injector in openshift

helm install hashicorp/vault --set “global.openshift=true” --set “injector.externalVaultAddr=http://external-vault:8200” https://github.com/hashicorp/vault-helm/archive/v0.5.0.tar.gz

(error in the above step)
Error: rendered manifests contain a resource that already exists.
Unable to continue with install: could not get information about the resource:
invalid resource name “hashicorp/vault-agent-injector”: [may not contain ‘/’]