How does the ember-cli-simple-auth-token library decodes/reads the jwt?

The ember-cli-simple-auth-token documentation specifies that the jwt is decoded and read upon successful authentication with the backend. However I don't understand how it will decode the token, the jwt is originally created with a private key but I could not find any information in the docs about providing the required data for the jwt decryption process.

What am I missing? How does the library decodes the jwt? Am I encoding it in a non-standard way? Is there a configuration property in the library to specify where to find the corresponding public key or something?

Thanks a lot to whoever reads this and can help.