Target Platform missing (OpenHAB1)

I am trying to setup a IDE for OpenHAB1. I am looking if i can help with the GC100 plugin. This one is not converted to OpenHAB2, and i still use openhab1 myself. One step at a time.

I followed this guide:
I fail at step 6. After the import i got a lot of errors (AbstractActiveBinding cannot be resolved to a type - i am not sure if these should appear “before” the selectin of the Target Platform).
But this Target Platform is missing. I only have " Running Plaform (Active)).

i used:

One thing to consider is that the old instructions you’re using could only theoretically work if you checked out the 1.8 branch from the openhab/openhab repo. The instructions would definitely not work with the master branch.

More generally, you would probably have better success if you used the modern IDE setup for openHAB 2. The newer setup also formats/cleans Java code according to the new standards. The binding changes you make can then be tested under your openHAB 1 installation.