Bee-cells-SMPlayer-green, Gears-SMPlayer, Shiny-buttons-SMPlayer, Smaragd-SMPlayer, Not-superflat-stickers-black-for-SMPlayer, Snowy-for-SMPlayer, Triangles-orange-for-SMPlayer, White-chips-for-SMPlayer, Yellow-square-for-SMPlayer.

Move all folders to .config/smplayer/themes/ or /usr/share/smplayer/themes/
Further - SMPlayer - Options - Preferences - Interface - Icon set - ******** - Apply - Ok

Full icon themes

Shiny buttons https://www.gnome-look.org/p/1012268/

Gears https://www.gnome-look.org/p/1012367/

Yellow square https://www.gnome-look.org/p/1150789

Not superflat stickers https://www.gnome-look.org/p/1152410

White chips https://www.gnome-look.org/p/1161701/

Bee cells https://www.gnome-look.org/p/1012466/

Smaragd https://www.gnome-look.org/p/1012162/

Snowy https://yadi.sk/d/kVzafq1ptMV4R