Not sure how Clarity did it but I can suggest a few things anyway.

1- Have your business plan and marketing plan ready and aligned to each other.
2- Have a concrete digital marketing plan as part of your marketing plan. Following is an indicative set of steps you may like to consider.

Digital Marketing plan-
1- Once you develop a digital platform, have it tested for engagement quotient (CTR, CTA etc.) and bounce. Resolve on priority if problems are found.
2-Implement a comprehensive SEO strategy.
3-Have a definitive user engagement and inbound marketing strategy in place. Such platforms can't rely on impulsive buying by customers. Content Marketing may be considered.
4-Get an offline fanbase ready to onboard initial set of users.
5-Once ready, launch a multi pronged digital campaign. Launch SEM and SMM campaigns to pick up the number of users. You may like to consider your acquisition costs carefully here but expanding fanbase will definitely require some investment.
6- You are up and kicking with a user base. Launch your further initiatives now.