Hello, yes the question is: on the first website WpForo is configured, how precess for transfering on a other WP configured website ? on the new website, wpforo without plugins is installed.
woForo is part of WordPress, in most cases you'll need to transfer the whole site along with the forum. For example your forum users are your WordPress users etc.
I suspect you may always hire an expert developer than can split the databases including users and other data etc, but honestly, just exporting the whole site with woForo is on is the way to go, you may always delete plugins, posts and other data you are not interested in from the rest of the site before the transfer.
This is not an easy task. All topics and posts are connected to users and user IDs, if the target WordPress already has some users then it's impossible to move. You should migrate data with regenerating all related IDs. This is a large work and can be performed by migration services like gConverter or ProfProjects.