First off: congratulations on shipping! Most never get there.Genuinely: Who cares about saving reels? Or less bluntly, who are your potential customers and where are you advertising to reach them?
Instagram itself is hugely popular, but the general population of Instagram users won't and don't care about saving reels. So either you teach them to (a la the story about the first shopping carts), or you find users who already want to, but don't have a tool for that yet, or are using a competitor's tool. Having not given it a ton of thought, creators themselves would want (and be willing to pay) for you're service. Play up the issue of if their account gets hacked or suspended by Instagram itself, they'll lose access to their reels and stories and posts, so use your service to get an off-site backup. Do you have AdWords setup so you come up when potential users search for your competition? Don't answer this, but what's your targeted/projected CAC (customer acquisition cost) vs LTV(lifetime value of a customer). You probably want to double or triple your ad-spend, but that'll raise CAC, so you want to have a examination of LTV before you commit to that.
Etc.
Contact a marketing agency for more in-depth specific help.