I'm trying to go through the Einstein Intent API basics module on Trailhead, and am trying to go back and download the einstein_platform.pem file which I closed out prematurely. 

https://trailhead.salesforce.com/modules/einstein_intent_basics/units/einstein_intent_basics_env

When I try to navigate back through to sign up I receive an error telling me I already have an account. Is there somewhere in Salesforce where i can download this file?

Any help would be appreciated.

Thanks