If you want to add the logotype to your Turnkey application, upload your logotype through portal.mdriven.net or MDriven Designer. Name your file "logo" and use .png or .svg extensions. The logo is placed in the _AssetsTK\SiteAssets folder.

You can also add a favicon to your application. Upload a favicon that is 16x16 pixels in size and has a .png or .ico extension.

It seems like we must use .ico files for them to show up as favicons. If you only have a .png, consider converting it here: https://convertico.com/

https://www.websiteplanet.com/webtools/favicon-generator/