The theme you have set is for GTK 3, while Nautilus uses GTK 4, so you'd need to have a GTK 4 version of the theme. Idk how to set GTK 4 themes tho.
Gnome
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Thanks! I will look it up!
I know that you can change the colors of Adwaita using Gradience, but don't know about icons
Thanks!
Don’t bother trying to download and install themes on GNOME anymore. The app developers were very tired of themes breaking the desired appearance of their apps as they had to be the one to fix it. GTK4 is harder to theme and is even harder with libadwaita as well. I recommend installing adw-gtk3 and using an app called Gradience to theme your apps manually.
Thanks