Installing on Windows with Bitnami WAMP stack gives requirements error

I tried installing the 8.0-alpha12 release on my Windows box with Bitnami WAMP Stack (PHP 5.4.28) - see https://bitnami.com/download/files/stacks/wampstack/5.4.28-0/bitnami-wam... for the stack.

As far as I can tell, everything is in working order. However, I get a lot of warnings from Drupal at the requirements step of installation:

    Warning: strpos() expects parameter 1 to be string, array given in file_uri_scheme() (line 290 of core\includes\file.inc).

    file_uri_scheme(Array)
    file_prepare_directory(Array, 3)
    system_requirements('install')
    drupal_check_profile('standard', Array)
    install_check_requirements(Array)
    install_verify_requirements(Array)
    install_run_task(Array, Array)
    install_run_tasks(Array)
    install_drupal()

  Warning: rtrim() expects parameter 1 to be string, array given in file_prepare_directory() (line 552 of core\includes\file.inc).

    file_prepare_directory(Array, 3)
    system_requirements('install')
    drupal_check_profile('standard', Array)
    install_check_requirements(Array)
    install_verify_requirements(Array)
    install_run_task(Array, Array)
    install_run_tasks(Array)
    install_drupal()

    Warning: strpos() expects parameter 1 to be string, array given in file_uri_scheme() (line 290 of core\includes\file.inc).

    file_uri_scheme(Array)
    file_prepare_directory(Array, 3)
    system_requirements('install')
    drupal_check_profile('standard', Array)
    install_check_requirements(Array)
    install_verify_requirements(Array)
    install_run_task(Array, Array)
    install_run_tasks(Array)
    install_drupal()

    Warning: rtrim() expects parameter 1 to be string, array given in file_prepare_directory() (line 552 of core\includes\file.inc).

    file_prepare_directory(Array, 3)
    system_requirements('install')
    drupal_check_profile('standard', Array)
    install_check_requirements(Array)
    install_verify_requirements(Array)
    install_run_task(Array, Array)
    install_run_tasks(Array)
    install_drupal()

After these errors, the red requirements message shows this:

File system 	
The directory does not exist. The directory does not exist. An automated attempt to create this directory failed, possibly due to a permissions problem. To proceed with the installation, either create the directory and modify its permissions manually or ensure that the installer has the permissions to create it automatically. For more information, see INSTALL.txt or the online handbook.

Perhaps this is Windows specific, it's not getting the directory names that should be created in this last error message. I can't proceed with install, either.