Thanks for replying, but I've taken a look at all these possibilities, building about 8 test leagues going through all the permutations, custom or not, and am more confused than ever.
There seem to be no options for playoff format in "Custom."
I pick variations of the "8 teams" in format, I get everything but what I'm looking for. I'll either get 1st to 2nd round the winner playing the winner in an opposite conference, or just the top 8 league teams regardless of
I have to say this is REALLY disappointing.

I realize there is so much customization in this game already but we should be able to say, "8 teams in each of 2 conferences, each conference 1v4 2v3." I've taken so much time to build test leagues under all these permutations of choices, can't get the result I want yet.
The options on the playoff type screen are too confusing and I wish they would be more flexible or explained more, or make it so we can export the playoff format and just make it ourselves.
I wonder if the devs can give us a more detailed explanation of the options on these screens. The documentation gives only passing reference and does not explain all options.