Those on demand freerolls, you can take some different approaches.
1. You can play tight, solid poker, let your opponents give you their chips when they have the second best hand. That forces you to rely on getting and making good hands.
2. You can splash around, playing loose. Here, you'd be taking an obviously higher variance line but you'll accumulate more chips faster if successful.
3. Picking your spots. This is probably optimal strategy as you can play tight solid poker and win some good sized pots with the nuts. But, you can change gears here and mix it up and apply pressure to your opponents in the right spots. It's up to you to determine where those spots are because it depends on your table draw.
Because those on demand freerolls are a dime a dozen, that's your opportunity to mix it up. Find out what works for your game.