Oauth authentication between 2 different workflows

Hi all,

I have 2 workflows to
#1 - register a user to an external site (this returns an access and refresh token)
#2 - update the profile (needs to use the access token)

Is there any way to obtain and use the tokens in the #2 workflow?
I’ve tried with a custom oauth token but the documentation on how to put dynamic data in the headers is lacking.

Also the #1 API call has no authentication as this is registering a user.

Any idea how to make it work?