SAP Build Process Automation - Permission Error

Hello SAP Gurus,

i am try to complete the tutorial for SAP Build Process Automation on my BTP Trial Account.

I created my workflow after the following guideline:

This is working so far.

Now i was working on the next part:

Under Step 3 i am facing a permission problem when starting a new instance:

Error:

I have all existing Admin/Developer Roles for Process Automation on the BTP Subaccount assigned.

Any ideas how i can solve this issue.

Thanks in Advance 🙂

Kind regards

Simon