Ive done this and it doesn't show up. Ive also gone to each individual Samsung app to check if notifications are turned off. 1)The icon I see show up on my phone has a Money 💰symbol, that symbol doesnt show up in ny existing apps 2) there are two samsung apps that l are grey and won't even allow me to turn the notifications off. I am a little frustrated. Thank you for your instructions 🙏 
You didn't turn on show system apps as per @Robin621k. Look at my screenshot. The amount of apps should be higher. You need to click where I marked and turn on show system apps. Then do a search for push services and turn off notifications.
You can't turn off the notifications in those apps because you do not have notification categories turned on. Settings/notifications/advanced settings/manage notification categories for each app. Turn them on. Then return to the app notification settings, tap on categories and turn off everything but the mandatory one from the store (which you can't). You will see there is a category for offers and events. Especially make sure that is turned off. You cannot turn off notifications from your Samsung account. That is not the app that's sending your advertisements anyway. Or, you can follow the instructions from @Robin621k and @Pianodude58 . Either would work.
