Connect product attributes in the other system with attributes in Norce, so the values are copied to Norce when products are sent.
Each row connects:
a Norce Attribute, and
an article attribute from the other system.
Good to know
If the list is empty, check that Norce is connected. An empty list almost always means the connection, not the setting. The same goes for the other system.
If a value is missing, create it in Norce first, then click Clear Cache on the settings page so the list is refreshed.