Questions?

I'm trying to embed a SendSafely widget within an Outgrow form. I'm currently trying to use a custom HTML widget, but I cannot get it load at all. SendSafely requires source to their script, but I'm not sure if Outgrow allows for that. Plus, it appears that the SendSafely embed script utilizes jQuery to properly map some variables and I'm not sure if that's possible either. Overall, just need to know if it's possible to embed something like that within in Outgrow or if I'm just spinning my wheels.