Same issue, I just opened the Samsung Members app to see if anyone else is having the problem and to my surprise.. there's a lot of other users who can't install the August update.
Using a Note 10+ 5G 512GB bought unlocked from a Samsung Experience Store.
I hope this isn't Samsung's way of telling us to upgrade to the new Note 20 Ultra
🙄
Current phone : Samsung Galaxy Note 10+ 5G 512GB