Can't get roter and hub to lock together

The wheel studs should press into, and be "locked" to, the rotor and then the hub. If they do not, then they are worn out and will need to be replaced. The only other location of difficulty will be the rotor centering on the hub, so check the mating surface on the hub for rust and debris that would keep that from happening. Especially be sure of this, since a wobbling rotor (caused by debris between the rotor and hub faces) will lower brake performance and cause more problems.

The wheel studs should have a knurled ring around their shoulder. These wedge themselves into the holes of the rotor. You may find it necessary to place a stud in, then "seat" it with a hammer and a punch. You can then press the two pieces (rotor and hub) together by installing and tightening the lug nuts (possibly with some washers as spacers to make up for the wheel thickness). An air impact wrench then makes this job a little easier, because it will spin the lug nut fast enough that the stud seats itself before it has a chance to turn out.

If you don't have that, a tie rod puller might prove handy - put the lug nut on the stud a few turns (leaving a big gap), then use the tie rod puller to try and pull the lug nut off (this will pull the stud into the back of the rotor, and should wedge it tightly in place). You cna then tighten the lug nut with hand tools, and the stud shouldn't spin.

And just for insurance, it's not a bad idea to recheck lugnut torque after you've driven the truck a few miles. Bryan