Norton Password Manager for Android doesn't automatically fill in credentials for Apps.
It depends on which app you are trying to use NPM with. It does not work for just any app. Norton has to add each supported app to NPM. There is no way to manually add new apps.
Here is the Norton product announcement that lists the apps supported by NPM. As you can see the list is from 3 years ago. I have been trying to get an update, but so far no new news.
If you are experiencing an issue that needs urgent assistance please visit our customer support area:
There are currently 4 users online.