The beatmap is currently using the default combo colors, meaning that the default colors from the skin the user is using will be used instead. You can change the colors in the Colours tab of the Song Setup menu, and if you want to use the default colors tick the "Enable Custom Colours" checkbox.
The lowest difficulty is too difficult for the drain time of the beatmap. Check https://osu.ppy.sh/wiki/en/Ranking_Criteria#rules.1 for more info on this.