I did not download or transfered it into doris. The geo-administration of the goverment uploaded this into Doris, based on the municipal cadastre. I just highlighted the border at the map for a better view and to compare easier.

I wanted to use the OSM data for a personal project, but was not able to use it, as the area is marked as "way" instead of relation and i could not export WKT-data from this.
Then I looked up at the official geo portal Doris that i maybe can get the data from them, but then i realized that the OSM data is wrong, as i compared the borders ... 

here you can find the official administrativ geo land-registry without my markings: https://wo.doris.at/weboffice/synserver?project=weboffice&client=core&user=guest&basemapview=or_flaewi

--> then you can search for at "Volltextsuche". Enter "Am Pfenningberg" – this is the location next to the Truppenübungsplatz.

You will get here: 
https://wo.doris.at/weboffice/externalcall.jsp?project=weboffice&stateID=e81e51f9-60cd-4c7f-987c-482410bcc853&language=de&user=guest&group_id=guest&client=core 

In this cadastre you will see a grey circle with "TÜPL" which is the abbreviation for "Truppenübungsplatz". Then follow the bold grey lines (and mostly bordered with XXXXX) and you see the same border which i highlighted.

You can also give this an automation as the usage of the geo-data portal is quite slow and tedious --> Just use the link above with the location "Am Pfenningberg" ( https://wo.doris.at/weboffice/externalcall.jsp?project=weboffice&stateID=e81e51f9-60cd-4c7f-987c-482410bcc853&language=de&user=guest&group_id=guest&client=core )

Then right mouse click and at the grey "TÜPL" circle. A small layer will open – then click "Was ist hier?" and wait for a few seconds – another layer will open (https://i.ibb.co/G93BfBp/Bildschirmfoto-2021-02-13-um-11-04-52.png

Click at "Ersichtlichmachungen - Sonstige Flächen (2)", then another layer will open at the bottom section of the website. 