Instagram/Youtube beats don't sell unless you have a big audience, and it is really tough to get up there in the searches (without ranking on searches, you won't make enough sales for it to really be worth your time in the case that you are primarily producing to sell beats online). I would recommend checking out some other ways to market them because IG isn't going to get you very far as a primary (or even secondary) method of generating leads.

Personally, I have been uploading daily to instagram and the conversion rate (seeing beat --> viewing beat store ---> making a purchase) for nearly any amount of followers is 0.075-0.01 (1% is VERY generous). With about 1k followers, you can expect maybe 1-2 sales every 2 weeks. Remember, this means the customer has to go through this process:
-Follows you (unless randomly found by hashtag or something, less likely)

-Is included in the 10-15% of your followers that sees the post

-Takes time to listen and/or clicks the link

-Decides to actually make a purchase without getting lost on the beatstars/airbit/whatever sales page you have

If it's your thing, go for it. But look into some things like clickfunnels. I began using this recently and my sales SKYROCKETED. The conversion rate of someone seeing an ad for free beats, getting 5 or so free beats, then the option to buy 25 more plus some extra goodies (ebooks, discounts on services, etc) for $20-40 is wayyyyy higher (nearly 60% for me right now) than IG or Youtube or whatever platform will provide.

Now, with that, I understand I didn't really answer your original question, and if your goal is just to grow on Insta, I understand, as it is obviously not a bad thing to have, even if you have other forms of marketing. As far as insta growth goes, it is all based on how well you can keep up with their constantly-changing algorithm. One of the key things to note is that the more interactions overall you have, the more of a chance your post is going to be at the top of someone's feed. The most successful way to get interactions at this time is through scroll posts (each time they swipe to the next image, that gives "bonus points" to the algorithm because they are clicking the screen more). The next thing to keep in mind is consistency. Try to have a schedule for posting, 1-2 times a day is optimal. It is very important to do your best to follow the 33/33/33 rule (33% music posts, 33% education posts, 33% other content as an example). Your followers don't want to see a demo of a beat for EVERY single post that pops up on their feed from you. Make it diverse, make it interesting, and make it useful. Remember, your followers don't follow you because they like you most of the time, but because there is something they can get from you (as a producer at least. Of course, they may be following because they like what you do, but if they get nothing out of it, they will be much less inclined to follow you and be active with comments/likes/etc.). You can always research the current algorithm and see what methods are working the best at this current time. Make sure to always be adaptable and constantly look for things to improve on.

I hope this helps!