Hi Janice!
Welcome to authoring in Articulate 360 and the E-Learning Heroes community!
Certificates of completion aren't supported in Rise 360 yet, but we are tracking a feature request for them. I'll add your voice to the report and will share updates if it makes it onto our Feature Roadmap.
While Scenario Blocks are a feature in Rise 360, if you require more custom interactivity for a scenario, I would suggest exploring 3-step scenarios in Storyline 360. In the meantime, I'll open the floor to our community for suggestions on designing this in Rise 360!