Download artifact from nexus

i am downloading .tgz helm artifacts from nexus
curl -k -u $nexus_user:$nexus_password “nexus-path-to-artifact.tgz” -o /tmp/xyz.tgz

When i am running helm command below-
helm upgrade helm-release-name /tmp/xyz.tgz -i --namespace $CLUSTER_NAMESPACE

i am getting below error -
"*.tgz’ does not appear to be a gzipped archive; got ‘application/octet-stream’

i checked whether those artifacts are avaiable or not at path by doing ls -ltr & .tgz files are avaialble.

i tried below as well to untar gzip -

tar -zxvf xyz.tgz , but its still not working for me stating error -
“tar: empty archive”

can someone assist what to do here?