Hi
You can set it so that appears yourdomain.com/portal
Go to ACP/server settings on Enable URL Rewriting: set to yes

I think I didn't explain correctly. After the portal installation there is no "portal" subfolder in my FTP. I tried what you told me but now the link redirects to http://site ...

Hi
You can set it so that appears yourdomain.com/portal
Go to ACP/server settings on Enable URL Rewriting: set to yes
I enabled the option but still I get a 404 page.

Now it redirects to http://site/subfolder/portal which is not correct. The portal for some reason is on http://site/subfolder/app ...

Your Portal Version: 2.1.0
Your phpBB Type: Standard phpBB3
MODs installed: No
Your knowledge: Basic Knowledge
Boardlink: http://paixnidi.org/mboard

What have you done before the problem was there?
Nothing

What have you already tryed to solve the problem?
Searched online ...