because"半个小时“is like a adjective,we can write this word in another way "半个小时的“,and “录音”is like a noun ,so “半个小时的”shoule be put ahead of the "录音”.your anoswer"我每天晚上听半个小时的录音“is right,maybe the computer needs a more formal sentence .We can say this as"每天晚上我都听半个小时的录音”.