If you already have a HelloSign account your company would need to have a HelloSign Enterprise plan with Salesforce enabled. This plan is available by contacting HelloSign Sales.
You can confirm that you have the correct account when you can "Connect" HelloSign to Salesforce from within the HelloSign for Salesforce app.
Don't have a paid HelloSign account? You can try out HelloSign for Salesforce for free! To qualify for a free 30 day trail you can either have a free account with HelloSign or not have an account at all.
For a full instructions on how to installing and use the integration please check out our Admin Guide.