How to add use-credentials for protected site

I have a site that is protected with .htaccess.

Even after entering the correct credentials I’m getting a 401 error on:
GET https://xxxxxxxxx.com/wp-content/uploads/fbrfg/site.webmanifest?v=xxxxxx

followed by a syntax error:
site.webmanifest:1 Manifest: Line: 1, column: 1, Syntax error.

It appears that the solution is to add: crossorigin=”use-credentials” to the manifest tag.

How can I do this using fbrfg?

Thanks!