Get URL Parameters - Decode & Save to Variables

Hello, I am attempting to use WeWeb to create an embedded app for my CRM, Follow Up Boss. The embedded app will be my WeWeb URL iframed into the CRM with 2 URL parameters (context and signature) automatically added to the iframed URL.

Here is the CRM documentation on how to create an embedded app:

I’ve added the javascript snippet, but I’m having issues figuring out how to save the 2 URL parameters to weweb variables. And then how to base64 decode the context variable once saved.