Uhhhh unfortunately they made the skin in a very dumb way, you'll have to open the skin folder and replace "default-0" through to "default-9" with those from a different skin (and of which dont have hitcircles around them, they're supposed to be just plain numbers).
If theyre still overlapped after that, you will also have to adjust something in the skin.ini file (located in that skin's folder). edit the skin.ini file and look for "HitCircleOverlap" and adjust it untill it looks right (the default value is -2. so try that). You have to save the skin.ini file with ctrl+s and reload the skin in osu (by pressing ctrl+shift+alt+s on a menu) each time you want to adjust it, otherwise itll stay the same
https://imgur.com/meHp7Mt