Unable to get Animated Weather Card working with current theme

I have 2 themes set up, whether the sun is up or down. When it’s down, a dark theme is automatically activated. The name of that theme is backend-selected.
I try to follow the instructions on how to change the current theme so it uses the Animated Weather icons (Very cool!) but whatever I try doesn’t work.

Under config I created a folder names Themes and, instead of a folder called ‘animated-weather-card’, I created a ‘backend-selected’ folder for my current theme. In there, a made a copy of animated-weather-card.yaml and renamed it to backend-selected.yaml.

In that .yaml file, I changed all lines ‘weather-icon-clear-night: url("/hacsfiles/themes/animated-weather-card/icons/clear-night.svg")’ to ‘weather-icon-clear-night: url("/hacsfiles/themes/backend-selected/icons/clear-night.svg")’ and copied all the icons in that subfolder. Restarted HA but still the icons don’t animate.
I am lost. I tried creating a new theme ‘Animated Weather Card’ and that works. But everything is white and bright blue and not the themes I have set up.
Trying to understand how this works but failing sofar.

solve this problem?

Not yet. Didn’t have time to have a closer look yet. I’m sure it can be done somehow.