Debugging an app from the Google Play Store? Is it possible to use USB debugging on an app that is not yours, and was downloaded from the Google Play Store?

I don't really need any in-depth information, I just want to be able to see general errors that may be occurring. 

I'm basically trying to debug a scrolling issue in my US Bank app on my own because their response is terrible, slow, and I've done redundant "troubleshooting" steps. 

The phone I have is a Google Nexus 5 running Android 6.0.1, which is not rooted.
On an unrooted phone you can enable the Android Debug Bridge.
When the phone is connected to your PC and the smartphone is unlocked you can log in via adb from the PC and see the logcat output of the app you want to monitor. 

If this is helpful for you depends on the app (some apps do log anything) and what you want to achieve.