There are multiple ways you can get new members to sign the waiver.
The most optimal way to get new members info into the system is to link to an on boarding plan from your website. After they hit submit the page will refresh showing the waiver to sign. It doesn't matter if your initial plan is free or paid, either way you can get them to sign up through that so when they walk in the door of your gym for the 1st time they have already paid, you have their basic info in the system and they have signed the waiver.
If for whatever reason they close the browser and don't sign the waiver online, when they go to check-in for the first time on the iPad the waiver will be shown and they wont be able to complete the check-in without signing.
If someone walks in off the street, you sign them up via the control panel as a Lead or as a Member. They can still go to the check-in app, punch in their name and the first thing that pops up will be the waiver for them to sign.
Email a person the waiver
Alternatively, once the member is in the system you can email them a request to sign the wavier. navigate to their profile page (use search in top right of any page), hit the 'Sign Waiver Now' button in the right rail.
Email everyone at once to sign the waiver
In the case where you have many people un-waivered, you can go to Reports -> Unsigned Waivers to see the list and send a waiver request from there. Also can be used if you update the waiver and want to revoke current waivers to get members to sign the new one.
Step 3 of the Migration Assistant, when you add the plan to the person, they will automatically be sent an email with a link to sign the waiver.