I had a 1080 before my MFT/3.
The MFT/3 is slightly higher, a slightly different dimension and it has a different set of side rails.
The fence, saw track, and brackets are very similar on the two units.
There are several videos on FOG or the Festool Youtube channel about squaring the rail to the fence. Start by searching there and the procedure is the same on either style of table.
If you have a set of dogs, it's even easier and no video or tutorial is needed. Square the fence along one dimension to the holes, then square the rail along the other dimension to a 90 degree set of holes and you're ready to cut.
Some purchase Woodpecker squares, but you can also use a carpenters square. I find the holes are my best reference.
And once you have things square, if you like, simply make a triangle out of wood and use that as a reference when you want to check it.
neil