You did not read carefully. Clearly written in OP and also discussed in some of latter posts.
You need content folder in igo folder. You just also create duplicate content folder in SD card, with most of the substructure.
In content of igo main, you put basemap, globalcfg, langs and voices, speedcams. Actually, all "static" data.
In content in SD card - all other: buildings, dem, maps, pois, phoeneme.