It looks like you are already in the guild. If for some reason you aren't you can click the ranking tab (golden trophy icon), then click the group tab. After that find the group in there and click on it then click join group. Clicking join group doesn't automatically put you in the group (unless the leader allows any member), so you may have to wait to be accepted. It's looks like you are already in the guild though otherwise you couldn't see what you see in the first picture. If the group only has 3 people you most likely won't get Minato unless the other members are spending coupons/ingots.

That just means it's a merged server. The group I am in isn't the same server number as myself. The server number for the group is solely based on who created the group.