First of all, the file you shared has a total of 33 slices, which means you want to extract 11 individual RGB stacks, is that correct?
Since this is a stack, you would need to use the Stack Tools.
What I would do is to first divide the stack in 11 parts using the Stack Splitter (Image > Stacks > Tools > Stack Splitter).
Then I would split again the individual small stacks in 3 separate images (Image > Stacks > Stack to Image) and reassemble them in a single composite image using Image > Color > Merge Channel.
You could also do “Stack to Image” from the beginning and then Merge 3 channels at a time to make the composite image.
If you are good with Macros you can create one to do all the steps at once.
I hope this helps!