Why does the download link from Windchill work in the browser but not in Electron?

I have built an Electron application which downloads files from Sharepoint. This works flawlessly. Soon the files will be transferred to Windchill and only be available there. When I substitute the download link with the link from Windchill, it doesn’t work, although the link works inside the browser.

When I open the Windchill main page in a popup window inside the Electron app, it loads without needing to login. SSO seems to work system-wide here, although I had to manually log in for Sharepoint. In the console the following message is show, which might have to do with the problem:

Blocked https://www.windchill.plm.com/Windchill/app/ from calling getURL on its opener.

What does this mean?