OK. Thanks again for your time and responses. I have referenced your original response and checked my settings in both SnapLogic and Box.
For the Box settings, the Redirect URI looks correct in the application. I have not created a triggered task for this pipeline, so I have not setup anything in the web app integration settings.
For SnapLogic, I have similar oauth2 settings in my account settings - the only difference being that I am pointing to a development instance of Box which uses a sub-domain of box.com.
When I go to authorize the account in SnapLogic, I am prompted to login to Box as expected, however am still receiving the error I quoted in my original post.
Could I be missing something in my administration configuration in Box? Do I need to explicitly grant some type of add the SnapLogic application somewhere? I can connect to the APIs just fine when using the Box developer token.