Where are the sitemaps in multisite

I have several sites in a multisite. I am trying to upload the sitemap to google search console. The path rankmath gives me is https://delia-fitandfab.patbell.co.uk/sitemap_index.xml but where is this in the ftp file structure, since the root public folder is the same for all sites in the multisite how does it differentiate between sitemaps? Its not in …/uploads/sites/siteid

Moreover google says it has a parse error on line 12.

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