You might want to get more info from your subscribers before they join your Messenger Giveaway. You can do that by editing the installed flows in ManyChat.
This can be useful if you want to get their phone number before they join or if you want to have them answer a quiz before entering.
To do that, go to your ManyChat account and edit the flow "VL Basic flow". You will see the "New participant" message that is sent to people that interact with your bot but haven't joined the giveaway yet.
Right after this one is the flow that submits the subscriber to the Viral Loops campaign, called "Participation API call".
So, to have your subscribers answer one question (or more) before joining your giveaway, add the questions as messages between the "New participant" message and the "Participation API call". Be careful though not to edit the "Participation API call" as this could totally break the functionality of the giveaway.
For example, here's how it could look like with one extra question:
Did you create some amazing flow? Let us know!