System setting does not allow changes to be made to object DEVC PACKAGE1

Hi,

I created a service Instance in SAP CP, which I embedded in Eclipse- as an "ABAP Cloud Project". A few packages are already populated (see pic1.png ).

But when I tried to create "PACKGE1" as a Sub ABAP Package of "ZLOCAL" (see pic2.png) I got a message that system settings don't allow changes to my ABAP package PACKAGE1 (see pic3.png)

My questions are: Which system settings are meant and what needs to be adjusted?

(I'm working with an SAP Cloud Plattform Trail Account.)

Thanks in Advance