I'm facing the EXACT same problem.
I used composer to install the files.
But, as the other Chris states, every single file I try to use seems to mismatch the folder structure.
I was able to get the GetRefreshToken.php to work, but only by virtue of editing line 19 to read require '../../../../../vendor/autoload.php', with an extra ..
Now, if I try to run any reports (eg. /vendor/googleads/googleads-php-lib/examples/AdWords/v201705/Reporting/GetReportFields.php), etc, they come up with similar directory structure problems, with similar errors on line 19.
Very frustrating!!
If I move the .php file itself up one directory, the GetReportFields.php runs but I get the following:
Fatal error: Uncaught InvalidArgumentException: Config file not
found as specified: 'adsapi_php.ini' or in the home directory:
'/Users/chris/adsapi_php.ini'. in /Users/chris/Google Drive/<my project's directory>/vendor/googleads/googleads-php-lib/src/Google/AdsApi/Common/ConfigurationLoader.php:63.................
Can you provide us with a sense of what the folder structure *should* look like?
That might prove exceptionally helpful for me, and others.