Most small places just use a basic WiFi marketing platform that gives internet access and collects emails at the same time. I set one up last year and it wasn't complicated at all. Customers type in their email and get connected right away. After that you can send them stuff about sales or events. Reviews where you can take a look at what others say helped me pick one that was easy to manage. Setup is connecting it to your router and making a simple login page. Costs around 30 bucks a month for basic plans. Way better than just giving out a password because you actually get something back from offering free WiFi