Can I make the carousel slider to have fix spaces between the slides?
No, you cannot. The way carousel sliders are working is, that as you make the screen smaller, slides will disappear one-by-one and the space between them will be distributed equally. This behavior cannot be changed.
You can find some alternatives in this documentation, but there won't be a solution, which perfectly fits this design. We suggest duplicating your slider to have a backup, and then you could change the slider type or just create a completely new slider.
In a showcase slider the space between the slides are fix. But its design is, that you will have one active slide in the middle, as you see for example on our demos, so it will behave differently from a carousel slider.
With simple slider type you can use row/col elements. The upside of this design would be, that columns are using % values for their widths, which is probably what you are looking for:
But the downside will be the mobile view. By default we are putting these columns under each other with the wrap after option. If you have 3 or 4 columns, the height of your slider will increase a lot. You could just hide some of the columns, to have a proper slider size, but this way you will have to lose some of your content, which wouldn't happen at a Carousel or Showcase slider.