People seem to overthink how to tame this guy so here's a simple guide:

1. Put on some ghillie.

2. Kill a baby rex or spino (wyverns and other similar tier dinos will probably work too, but I haven't tested them).

3. Drag it to the charchar.

4. Profit.

If you want to be fancy/safe, you can make a typical behemoth stone gate cage trap and lead it in. Yes it can break stone, but it won't be in the trap long enough to do so. Once you drag the dead baby in, open the gate and have fun on a rampage. Ghillie is there so the baby corpse doesn't accidentally get chomped while the carchar is trying to kill you.

No need for wasting metal on some overly complicated gate and bear trap setup.