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 installed by the App Store is: root

The correct owner of an application bundle within /Applications for drag and drop user installed apps is: $USER ¹

¹ 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. Otherwise, use the short name of the USER who is to own the file.

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.

Apps that are installed by the system, either out of the box or by an installer that asks for an admin password, will be owned by root. Everything installed by a user (i.e. drag and drop) will be owned by whoever installed them, which is where you seem to be running into issues if you require write permissions for updating and a different user installed that app. All of these possibilities are valid ownership.

You can safely change the ownership to yourself if you need to, or else you can use group permissions so that, for example, all users with admin privileges could update the app.

The below code changes the group (all files/folders in the .app package recursively) to the "admin" group, which all your users with admin privileges will be a member of, then adds write privileges for the group. You may need to use "sudo" at the beginning of each line if you don't already have suitable privileges.

> chgrp -R admin /Applications/Fritzing.app
> chmod -R g+w /Applications/Fritzing.app