Anonymous. You are not authenticated in phpBB now"

I would say to try these two approaches. Do one first to see if it works, and the other, if both doesn't let me know.

1. Try copying the functions_user.php [from the mod] to the one located in phpbb3's directory. Overwrite if possible.

If that doesn't work try this.

2. Rename functions_user-3.01 to functions_user.php locally in a different folder (to avoid overwrite issues) and then upload it to the phpbb3 directory of your server.

If that all fails, make sure that the directory containing the functions_user.php [the p hpbb3's version] is writable (same with the folder) so that you can overwrite the existing one.

i have same issue

i've do all like in instruction

Successfully locating phpBB installation.
Successfully locating /www/pawi_www/www/forum/includes/phpbb_api.php.
Successfully connected to the phpBB database.
phpBB user: Anonymous. You are not authenticated in phpBB now. Please login to phpBB and test again.

i'm logged in in my phpBB forum with the same username and password like in drupal

I resolved this issue by deleting phpBB3/Cookie Settings/Cookie Domain (Blank)
as specified in Issue #293233: Authentication between drupal & phpbb:

------------------------------------------------------------------------
I have gone through the same procedures. I initially tried to run phpBB3 v3.04. It appears that when you login as Administrator that both Administrator and Anonymous usernames are logged in at the same time (Not so with phpBB3 v3.02).

I wiped my Drupal, phpBB3, and phpBBforum Installations and started fresh with phpBB3 v3.02 to match the version of the function_user.php file, version 3.02.

It appears that phpBBforum module tries to use "Anonymous" User login credentials regardless of the Administrator login chosen for both Drupal & phpBB3. I am wondering if username "Anonymous" is hard coded, or otherwise referenced, instead of a variable pulling the username from the currently logged in Drupal Administrator.

For testing sake, I banned username "Anonymous" from phpBB3. The following error appears in phpBBforum Admin Panel:

* user notice: You have been permanently banned from this board.

Please contact the Board Administrator for more information.

A ban has been issued on your username. in E:\xampp\htdocs\v6\phpbb3\includes\session.php on line 1135.
* user notice: You have been permanently banned from this board.

Please contact the Board Administrator for more information.

A ban has been issued on your username. in E:\xampp\htdocs\v6\phpbb3\includes\session.php on line 1135.

My phpBB3 Cookie Settings are:

Cookie Domain: [Correct domain specified - same as url]
Cookie Name: phpbb3_4geqy
Cookie Path: /

My phpBB3 Server Settings are default and:

Domain Name: [Correct domain specified - same as url]
Server Port: 80
Script Path: /phpBB3