Unuopa is valid in this case but unuope is much better. Unuopa is an adjective, so someone might understand it like "Lonely Sofia does not like to travel". Then it could be argued that "Sofia" and "unuopa" are so far away from each other in the sentence, that "unuopa" is an apposition, which would cause the meaning of the sentence to be "Sofia does not like to travel as a lonely one".
Unuopa is therefore valid and correct but unuope is better, because unuope conserves the freedom of the word order and avoids this possible double meaning.
Literally it means "in a group of one (each)". But if you always travel in a group of one, you travel alone, so it does make sense.