Before starting to import cells from a csv file, you should be sure your .csv files are ready for importing. Different files for different technologies. NSG only can store one database for one network. If you are importing a database that existed in your old database, the old cell database will be removed and will be replaced by the new database. Please be aware. If you’d like to merge all the database together, you can do that in the csv files.
Besides, cell database importing is supported in a paid version. In free version, cell can be imported, but it cannot be shown in cell table and map.