Errors compiling the example of goole vision

[ComptonAlvaro]

I would like to develop an application to scan QR codes using google vision, so I download the examplo that there is in this web, but when I try to compile the project, I get some errors, like some methods are not found or override or or Barcode type is not found.

Also in the using, the namespaces using Android.Gms.XXX are not found too.

Thanks.