What's the question? Do Rangers have to choose a type to scan for? No, they scan for all 7 types in one go, and the return information would be of the format "there are some undead and some fey detected in range, but none of the others" then as the Ranger walks in a direction with the Awareness active the DM might need to announce things like "there are no undead in range anymore" or "you now detect fiends in range".
The only choice for the Ranger which the feature implies is that in their favored terrain they can choose a search range between 1 mile and 6 miles.
Both wordings mean the same thing if you read the whole context and not just the list. If any one of the creature types is present it tells you that there's something not right nearby. Most DMs will houserule that you know which type at least, but by RAW you only know whether an odd creature is present or not.
Rephrasing it a bit:
You can detect A, B or C if they are present.
You can detect D if they are present. D consists of A, B, and C.