www programming

Hello.
I have just installed a fresh new wordpress 4.9.7 and the latest version of the plugin. I followed the instructions and I am sure that I made a mistake somewhere becouse now I can't login to wp-admin area. In fact, when I enter my username and the password it redirects me to the homepage and not at the admin area. If I delete the folder of the plugin I can see and I can login at admin area.
Here is what I did. I have to say that I am doing this at my localpc using xampp.
-Installed wordpress "on top". I can see it at http://localhost/
-forum phpbb was allready installed at /forum or http://localhost/forum (version 3.2)
-Installed your plugin
-doing some edits at phpbb acp (cookie, etc)
-Returned to wp-admin to make a page etc and I noticed that I was not login. I tried to login but with no luck. All I can see is the homepage.
-So I deleted again the folder of the plugin

Do you have a clue what is happening and how should I procceed? Please advise.
THANK YOU!

Hi! This look like to be a cookie problem.
The integration (like WP) work with cookies.
Once installation activated, the plugin search for a valid phpBB cookie, that can be found if you've login in phpBB, AND you have setup phpBB to release it as available over all the domain.
While when you login in WP side, the plugin release a phpBB cookie that will be available into phpBB.
In your case something goes wrong.

What cookie value in phpBB ACP have you setup, about domain and path?
localhost and /
??

are you under https in one cms and http on another?

Please let me know also if u can:
since you're testing into localhost, and your is a fresh installation, i assume your user is the user ID 1
what username you've setup for him, and what is the installer username of the user in phpBB?
They have the same email address?

Thank you for the FAST reply!
Please look at the attachments. Theese are my settings.

As for the users
At wp , you are right, my id=1 and username and email is the same as on phpbb.
On phpbb my id is diffirent. It is 169

But I can't go at plugins settings. If I reinstall it, I can't go to wp-admin. How can I reinstall it correctly?

Set Cookie domain value as:
localhost

Save. Logout the phpBB user and Clean cookies. Try out now.

p.s i see now ...

On phpbb my id is different. It is 169

so the related phpBB user that is with ID 169 in phpBB, is the one that have the same username and same email of the installer WP id1?
That's right?
mh ... let me check this scenario and what happen ...

I did that.
Logout from phpbb
Logged in wp
Installed again the plugin. When I hit activate it logs me out and it goes to the homepage. The only thing that I can do is delete or rename the folder of the plugin so I can login again at wp.
Do i have to delete something from db?