Before you buy anything be sure the bike fits. If it's too large or small riding will be more difficult and more uncomfortable than necessary and possible unsafe. If it's a decent fit, the bike you linked to seems suitable and not in too bad shape.

Do you have a knowledgeable friend who could go with you to evaluate it? Is there a bike co-op in your area that will have used and refurbished bikes at low cost and have some expertise to guide you?