I would like to suggest a better way than using the folio. The folio is like the subject line on an email: its purpose is to quickly convey to the user brief information about the workflow instance. It is not generally used to store data.
In your first form where you submit the request, you are probably using a SmartObject to store the data, maybe a database, a SharePoint List, or some other data store. When you store it, the SmartObject should be set up such that returns the unique identifier of the record that was stored. If you are using a database that would be the primary key.
In your workflow, create a datafield of a compatible data type to hold this unique identifier. Then in your submission form after saving the data, start the workflow passing the unique identifier to the datafield in your workflow. In the next user step in your workflow, you can pass this datafield as a querystring parameter to the form. The form when it opens uses this parameter to load the appropriate data from the datastore via your SmartObject.
If you haven't had a chance yet, you might want to check out the product training available on Nintex University. As you progress through the training modules it guides you through building an application with the technique I discussed above.