If you're on a paid subscription, you'll be able to create as many nodes as you'd like.
For example, you can run a 4-week long campaign, two 2-week long campaigns, or four 1-week long campaigns. The length of the campaign can even be customized to 1-2 days.
If you're on a free subscription, you'll be limited to working with up to 3 creators/month.
If you'd like to create 3 separate nodes (with 1 creator each) or simply run 1 campaign with 3 creators, you can do so.
Be sure to note that for both subscriptions, your nodes will not be able to overlap each other in dates.