[Plugin: PHPBB Single Sign On] Notice: has_cap was called with an argument that is deprecated since

Hello everybody,

I have problem with this modul:

I have phpBB installed in wordpress subfolder /forum, and all configurations seem to be OK

but after this modul installation I can′t correctly log-in into WP and same bug is in the phpBB too.. After login input I obtain only white blank page

I am enabling display_errors On public_html and after this, WP shows me error warnings:
Notice: has_cap was called with an argument that is deprecated since version 2.0! (in Slovak lang)

https://screencast.com/t/GQDZvnGnG
as you can see at screenshot

and Notice: Undefined index: stage in /home/export/html/zahradnictvopodurpinom.sk/public_html/wp-content/plugins/phpbb-single-sign-on/options.php on line 10

and whole system seems to be instable

After clicking at link https://www.xxxxxxxxx.sk/wp-admin/plugins.php?plugin_status=active I can administrate site but warnings still appear in head of page or between admin menu items

This changes I was make after installing this module :

auth_wpbb.php
This file must be copied from

…./public_html/wp-content/plugins/phpbb-single-sign-on/files/auth_wpbb.php
to
…../public_html/forum/includes/auth/auth_wpbb.php

common.php
It seems that this file is the original common.php file.

you will have to rename this file

from
common.php
to
common-orig.php

the file is in the folder
……./public_html/forum

This file must be copied from
……./public_html/wp-content/plugins/phpbb-single-sign-on/files/common.php
to
……../public_html/forum/common.php

https://www.ads-software.com/extend/plugins/phpbb-single-sign-on/