I mean, here's the deal.
How do you fix it? You need to find what they call a lower inner door patch panel, and depending what the outside looks like, and outer lower patch panel.
That LOOKS like a car with bad dew wipes, bottoms of doors filled with crap, that held water, and it rusted. So outer may not be bad except some small patches.
Now, if nobody is making those stamped inner panels anymore (nominally cover the bottom 4-6" of the inner part) then it's not really something you'd piece together yourself.
Either way, your time is ahead to get replacements and the jamb stickers can be reproduced with your car specific data.