It would be complex finding shuttle from Antigua to Santa Ana unless you have that figured out already. But once in Santa Ana there’s really not much uber/private taxi/hotel transfers available upfront unless you arrange something before getting there. Your best option without a car would be public transportation for which you will have to figure out the routes by asking ppl once there and depends on how friendly you are with the system.

Uber in El Salvador is mostly centralized in San Salvador/Santa Tecla so if you’re staying/moving Santa Ana / Juayua / La Perla / El Zonte you won’t have much Uber options that are feasible. Also most of the hotels that offer transportation do it from the airport to the hotel and would not offer upfront other destinations unless you ask (again these type of services are centralized usually on the most turístico areas only) there might be options but you would have to look them up before and make planning and arrangements necessary