You can be as restrictive or open as you want - based on age (and select multiple age groups that qualify, like children and teens), traits, careers, and several other criteria, and you're able to select multiple choices from these categories - if this weren't the case, it'd be rather bland.
Here are the main features of clubs: Choose entry restrictions, activities, personality traits, and other membership requirements for your club - you can then choose what type of activities the Sims will do when the club meets up. You can choose which of your Sims will be involved in clubs, and even try to join specific exclusive clubs. Having dedicated clubs and perks for participating in them, will help immensely in alleviating this flaw in The Sims 4's base game. Clubs seem promising, given many of us don't have a lot of reason to get Sims outdoors and explore the various neighborhoods. There are some pre-existing clubs around town, but many players will enjoy making and customizing their own. Like Get to Work, this is where we get the whole name for the Expansion. Clubs are the single biggest feature of this Expansion Pack, and are far better than many first imagined them to be.