I have it set up in our test environment. It works well.
There are two main licences types, "Foundation" and "Complete".
https://www.cisco.com/c/en/us/products/collateral/plus-as-a-service/secure-connect-now-ds.html
Then there are two flavours. "Essentials" is basically (not quite correct) for when you have 10 or less users. Otherwise you need "Advantage".
The big difference is that "Complete" includes zero trust support. This allows you to access an internal web page or service without the user having to do anything. It users the zero trust module of Cisco Secure Client - which requires no user interacton.
It comes with Umbrella. It integrates with Cisco Duo - so you need to still buy Cisco Duo if you want to use it for your SAML provider. You can also authenticate against Entra ID.