Nordigen REST API - ressource variable problem

Hi at all,

I am working with the Nordigen API to get bank transactions.

https://nordigen.com/en/

They offer a free account to get this data !!!

I am trying to follow this quick setup with the REST functionality of PHPRunner.

https://nordigen.com/en/account_information_documenation/integration/quickstart_guide/

Till step 5 I managed everything and got the desired data.

For step 6 you need a ressource URL like this

https://ob.nordigen.com/api/v2/accounts/065da497-e6af-4950-88ed-2edbc0577d20/transactions/

Problem is, that the code after "accounts" and before "transactions" is the account ID from the step before, but the account ID isn´t part of the response. So I have no chance to setup a relation between the data from step 5 to the data of step 6.

How or with what variable then am I supposed to get the transactions from the right account? How do I create the ressource URL with variable data that is not part of the "insert variable" choice? Can I use Session-variables? How?