Regex for space and other characters not working

I’m having problems generating field value or the regular expression type.

I tried using patterns with \s for space characters like this pattern \d{3}\s{1,3}\d{3}, it didn’t recognize \s as a space character, rather.

I also tried patterns like this [:alpha:]{2}\d{2}[:upper:]{2}\d{10} and it doesn’t interpret the [:alpha:] as alphabet characters and [:upper:] for uppercase letters. It treats all the characters inside the square backets as possible character options literally.

Any suggestions? Thanks!