Q: After I passed the last step of install I was not forwarded to admin area/I got 404 Forbidden error. The error also occurs on the main page.
A: The problem is usually fault of mod rewrite rule not working.
Solution: First thing to check is if have downloaded the most recent Boss Cart release. Second - if your hosting account supports mod rewrite rule (90% hostings do). If so check if it is 'on'. (Ask you hosting provider).
If you're still having problems please post them in our forums, most possibly in this section:
Bosscart Installation Help