what is the correct ownership for files in /Applications
The correct owner of an application bundle within /Applications for preinstalled Apple apps is: root

The correct owner of an application bundle within /Applications for packaged installers user installed apps is: root

The correct owner of an application bundle within /Applications for drag and drop user installed apps is: $USER

Where $USER is typically the short name of the person who installed the app. Otherwise, use the short name of the USER who is to own the file.

Here are the results of the ls -leO@d command run from Terminal on the Fritzing application bundle:

$ ls -leO@d /Applications/Fritzing.app 
drwxr-xr-x@ 3 me  admin  - 102 Jun  6  2016 /Applications/Fritzing.app
    com.apple.quarantine     57 
$


Same command run on the directory mentioned in the error message shown in the OP:

$ ls -leO@d /Applications/Fritzing.app/Contents/MacOS/fritzing-parts 
drwxr-xr-x@ 15 me  admin  - 510 Jun  6  2016 /Applications/Fritzing.app/Contents/MacOS/fritzing-parts
    com.apple.quarantine     57 
$


To change owner of a user installed app, e.g. for Fritzing, use the following command in Terminal:

sudo chown -R $USER /Applications/Fritzing.app


Note you can leave $USER as is written if you are the logged in USER and you are taking ownership.

Also consider checking the permissions and adjust as needed. As in this case for Fritzing:

sudo chmod -R 0755 /Applications/Fritzing.app




As I have Fritzing installed and working, and its permission are as previously shown, I believe the error message is somewhat erroneous and is being caused by you not being the owner. Changing ownership as previously shown should resolve your issue.