Charge HQ is currently in beta testing. This means frequent changes and occasional bugs.
Charge HQ is currently free to use, and anyone may create an account.
To get started, download the mobile app.
You can also access Charge HQ via a web browser at: https://app.chargehq.net.
Both the web app and the mobile app can be used in parallel. The web app can't do the initial connection to a Tesla account (you need to use the mobile app for that) but it can do everything else and is often the easiest way to setup any account where you need to copy-and-paste keys, e.g. solar inverter credentials.
Once you have the app, getting set up usually only takes a few minutes, although it may take a bit longer if you need to configure your smart charger. The following articles may be helpful when getting started:
You'll find many more guides and FAQs in the support section.
There is also a Facebook group for members of the beta program. It can be used for asking questions, raising issues, making suggestions or any topic related to Charge HQ and EV charging.