Your HOA/COA uses Memberment to control access at your pool. When you arrive at the pool, a pool attendant will scan your Memberment app code (found in your profile), ask your name, compare your photo on file, and then mark you as "checked in".
The attendant will check in all members of your household with you, too. There's no need to scan each member's code.
If your HOA/COA allows guest passes, then your guest passes will be seen by the attendant when scanning your code. If you need to buy more passes, then the attendant will need a credit/debit card if one is not on file.
Here's a video showing you how it works: