I just tried myself, the easiest way should be to simply import the oekobaudat as database via the ILCD network import,
then select oekobaudat,
then select all (ctrl-a), and then import
But indeed there are many errors thrown.
If you check the log file, you will see many errors similar to "no reference flow property provided"
These are inconsistenies and plain format issues in the official oekobaudat database. We have an older version of the oekobaudat on Nexus, where these issues have been fixed, but I will also contact the data provider for the oekobaudat.