If you get a message about terms when trying to deploy a charm, it means that the charm you're attempting to deploy requires you to accept some terms and conditions. You do this via
juju agree <term>/<version>. You can get more info on that with
juju help agree. The message that you get should indicate which terms you need to accept, but you can also find out using
charm show <charm-url> terms (e.g.,
charm show cs:~ibmcharmers/ibm-http terms).
charm push-term command is for creating a new terms agreement for charms that you create. If you attempt to push a new charm to the store using
charm push which says in its
metadata.yaml that it requires a certain version of a terms agreement, that agreement will need to be pushed first.
The current version of the charm command is 2.2.0 and is available via snap, as previously mentioned, or via the Juju PPA
ppa:juju/stable, with the snap being the recommended way to install and keep up to date. The terms functionality was a recent addition to the charm command, which is why it is not available in 2.1.9.