How to upgrade Sugar Professional v7.7.2.0 up to the latest version?

Good Day!

I would like to know where I can download the old patches of SugarCRM Pro from v7.7.x up to v8.0 since these files are not available on the Sugar Customer Portal. We want to update SugarCRM Pro step by step rather than skipping over previous versions and going straight to the latest version. This is to see what customization is affected and how big the impact each upgrade has on us.

We never upgraded it before since we never encountered any errors, and it is working fine. But right now, due to security concerns because of the latest exploitation in SugarCRM, we'd like to upgrade it from 7.x to 12.x. Hopefully, someone will be able to assist or advise us on this matter.