Yes, you are right about the Input.
Normally the fields are called with the same name as in the underlying Domain Manage, e.g. the CMDB.
Here you would have to look for a filed called "asset_num", possibly "Asset Number" or something similar.
I don't have access to a CMDB right now, so cannot clarify that exactly.
The policy also shows an alternative (commented out) using the system_name as DBInstanceName. if this makes more sense to you, you can activate that line instead of the one with asset_num.
If you look at the RAW data, you might also see something else that might make sense as DBInstanceName and you can map that attribute.
If you modify something in the policy, you should also keep the attribute name in the conditional part identical. This makes sure that the value is only used if it is set.
The first line in the policy setting the DBInstanceName is weird: it just blanks out the attribute, e.g. if the second line, using asset_num, is not evaluated as true, the variable is blank and thus the CI will not be created.
And after policy modifications you have to restart the Connector.
MichaelBoehm