Google shows highway 319 crossing the Amazon River.
Satellite view shows nothing there. Is it a ferry? Or just wishful thinking?
Yes, there is a ferry there. It runs from Manaus to Careiro da Várzea.
Here's a street view of the other end:
The Amazonas government appears to operate a scheduled ferry service between 5 am and 8 pm daily which can carry vehicles. The trip takes 1h20m. This is in addition to private ferries and boats, some of which do not carry vehicles.
It doesn't appear to be possible to book this ferry in advance. As far as I can tell, you show up and it's first come, first served.