Some Questions 2

[Admin]

Usually cPanel creates subfolder for Addon Domains in website root folder.

Bridge require master site.com to be http://site.com and phpBB should be loaded via http://site.com/subfolder (e.g. http://site.com/phpBB3), same domains.

[LOWW]

Its possible to run under forum.test.at ?
I see its better when I make a redirect from my websitenameforum. at to -> forum. test. at

[Admin]

No, Joomla and phpBB should use same domain name.

[LOWW]

main domain: (for example) test.at and the forum could be forum.test.at?

[Admin]

No, these are different domains.

Joomla should be installed in root: http://site.com
phpBB should be installed in first-level subfolder: http://site.com/phpBB3

Bridge menu item URL will be like http://site.com/forums