After the interaction with your external tool ends, you have the possibility to ask for contact information. To increase the likelihood that someone will actually enter their data, you should give them a good reason.
People will ask: What do I get in exchange for my email address? Do I have to worry about annoying spam?
So think about what you can offer. Maybe share the results of a survey? Or send a free newsletter? Do you ask for permission to contact people again with a personal request? Or can you offer to send them something like an ebook or other interesting content?