Single page app (SPA) monitoring comes with the default install of the browser agent.
You can review compability and requirements for SPA monitoring here.
When you set up your first monitored app in a New Relic account, you must agree to the Terms of Service. By agreeing to the terms, you authorize New Relic to collect hash fragments from URLs. You only need to select the checkbox option once for an account.
When you enable browser monitoring, SPA monitoring is included by default because it gives access to a range of our most recent features, including distributed tracing. Some older agent installations may need to be upgraded. Read more about browser agent types.