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 in 16x16 pixels size and with a .png or .ico extension.

It seems like we must use .ico files to show up as a favicon. If you only have a .png, consider a conversion from here: https://convertico.com/

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