From the manual: "A task is fulfilled if the colors shown correspond to the four horizontally or vertically adjacent tiles' colors". It seems to me there's no red adjacent to the blue 6 tile.
Have you read the rules? It says then: "A neighboring color is counted more than once if a tile has a neighboring tile of the same color. This can be continued as desired: Count all horizontally and/or vertically adjacent tiles of the same color together."
you have to complete the tasks by placing the pieces on one of the 4 edges of the tile, the color needs to be touching the tile.
if a tile of one color is placed adjacent to a tile of the same color, all tiles of the same color that are adjacent to another tile will count towards that tile's task.
Forgive me if my text is very confusing, I used google translator to translate.