Great! Thanks for your help!
If someone else goes through this, in order to avoid the "complete installation" screen from showing, you have to edit a value in your OpenGoo database. What you have to do is, in the 'og_companies' table, set the column 'client_of_id' of your company (the company with id 1) to 0, which in SQL is:
UPDATE `og_companies` SET `client_of_id` = 0 WHERE `id` = 1
Note that you may have a different table prefix in your installation than 'og_'.
We'll solve this bug for next release.
Thanks again thetitan!