Can't cURL information from Elasticsearch cluster - elasticsearch

Question

I am trying to install and setup Elasticsearch on a remote Machine running CenOS7 via this guide. Following the install and start instructions for RPM I entered the cURL command given on the guide to check its up and running: curl --cacert $ES_PATH_CONF/certs/http_ca.crt -u elastic https://localhost:9200
I was met with the following message:
curl: (77) Problem with the SSL CA cert (path? access rights?)
I tried to go to the domain with the following command:
curl https://localhost:9200/
And was met with this:
curl: (60) Peer's certificate issuer has been marked as not trusted by the user.
More details here: http://curl.haxx.se/docs/sslcerts.html
curl performs SSL certificate verification by default, using a "bundle"
of Certificate Authority (CA) public keys (CA certs). If the default
bundle file isn't adequate, you can specify an alternate file
using the --cacert option.
If this HTTPS server uses a certificate signed by a CA represented in
the bundle, the certificate verification probably failed due to a
problem with the certificate (it might be expired, or the name might
not match the domain name in the URL).
If you'd like to turn off curl's verification of the certificate, use
the -k (or --insecure) option.
So I tried the previous command once adding a '-k' but was met with this error:
{"error":{"root_cause":[{"type":"security_exception","reason":"missing authentication credentials for REST request [/]","header":{"WWW-Authenticate":["Basic realm=\"security\" charset=\"UTF-8\"","Bearer realm=\"security\"","ApiKey"]}}],"type":"security_exception","reason":"missing authentication credentials for REST request [/]","header":{"WWW-Authenticate":["Basic realm=\"security\" charset=\"UTF-8\"","Bearer realm=\"security\"","ApiKey"]}},"status":401}
I was able to complete the guide on my MacBook but have almost no experience working with remote machines or in CentOS 7. How do I successfully cURL the cluster information?