What app are you using? So far none of the apps support it what I did is I just screenshot my recording from cat box moe.

Go to catbox moe, upload your media, then copy the link and paste it in your browser and open it, play the audio screen record it and then save it and you'll be able to post it. You can also add audio to highlight reels if you can create highlight reels on your Samsung but mine's fucking up for some reason