Hi Gal and welcome to the Lithium community,
Just to get it out of the way: Lithium Community itself cannot act as an SSO as the authorization server. But Lithium Community can easily use your existing SSO infrastructure to have your customers authenticate against that. introduction to this concept is available here: https://lithosphere.lithium.com/t5/Single-Sign-On-SSO/About-Lithium-Single-Sign-On-SSO/ta-p/108917
For your scenario you might not actually need a complex full SSO setup though: Lithium Community has roles and associated permissions built in. That means you could assign a customer (or even individual product) role to your community members. Then you can create a custom component on your Lithium Community pages that checks against the presence of this role for the current member and would only include your JavaScript SDK to embed the iframe with your content if that role is present.
You can assign these roles after a manual review / matching with your CRM record or if you go for the SSO route have them automatically populated with the product records from your CRM.