Hi Maura,
Dont think there is a car hire company in Almerimar to be honest, someone correct me if I'm wrong, so best get from Airport. However I have been told its impossible to get car hire in Spain at present. I know ones who went to both Almeria and Murcia airports and were not able to get them. Best bet is to start searching the net using google or something and you might get lucky.
Sorry the news is not better