My backup phone (Galaxy S8+) has the same issue, so what I do every time the apps don't want to download the updates, is to turn off the phone then turn it back on, and that works for me.. Do not restart, instead turn it off.
P.s. I reported the issue to a Samsung specialist, and he told me It might be a system error
It's more than likely something to do with Google, and not your actual device. I work as customer support for 3rd party Google, and your best bet is to try the steps here:
Hope this helps!