Ask them for feedback on why your application wasn't successful this time and what they think you do to improve your chances of employment with them in the futu

Ask them for feedback on why your application wasn't successful this time and what they think you do to improve your chances of employment with them in the future. They still might not give you any, but in my experience most places will. Then you can take their feedback into consideration for your next application. Sometimes it'll be something you can't do much about quickly (e.g. if there was a candidate with more experience than you). Other times though you'll discover a quick win (e.g. your application didn't clearly state your relative skills or experience).