It's pretty simple.
Freo lose - Freo finish 6th
Freo win + Collingwood Win + Sydney win - Freo finish 5th, unless Melbourne and Brisbane draw then Freo finish 6th.
Freo Win + Carlton Win or St Kilda win - Freo finish 4th, unless Mebourne and Brisbane draw then Freo finish 5th
Freo Win + Carlton Win + St Kilda Win - Freo finish 3rd, unless Melbourne and Brisbane also draw then Freo finish 4th
Freo win + Melbourne and Brisbane draw and St Kilda and Sydnet draw - Freo finish 5th if Carlton Win or draw or 6th if Collingwood win.
There's a couple more 5th and 6th combo possibilities involving multiple draws, but essentially, 3rd to 6th is in play.