Fuck you apple!!!
I wanted to add some old audiobooks I have in mp3 format to my wife's Iphone...
Ok, connect it to the computer. No direct file transfer. Start iTunes...updates... Import library..ok.. it's imported locally but sync then???
Sync purchases.. no
Mark stuff and move.. no way (got it playing in chrome somehow when trying to unmark everything)
Got to "buy stuff now page".. close it iTunes.. start it again and come back to same page..
Then I.. shamefuly Google "transfered audiobook iPhone" and got all the pages how to sync when you already bought items from appstore...
...
Eventually I transfered the files folder by folder. There is probably a better way to do this but I were at the ends of my rope so I archive this as a narrow win.