Are you sure you downloaded the ISO with non+free included?

For the longest time Debian kept separate ISOs for the non+free drivers, boot stuff, etc. and the user had to search the site for them. Recently with the latest release of Debian Bookworm the Debian maintainers stopped separating them and put the non+free stuff in the main ISOs. If it was more than a few months ago that you tried installing that could be the reason you had problems. I’m not saying that it is, but it could be.