I agree with the previous posts about patience and high-quality content. But I'd also caution against the idea that it is easy to convert IG followers into sales of your product. For example, I have a close friend who has spent a couple of years building up to 130,000 IG followers. When he tried to sell his own online course, he converted a tiny fraction of those followers into customers (fewer than 50 signed up; that's .03% or .0003).
Most online businesses continue to argue that an email list is a far better way to sell things to followers. Of course, you can use IG to get people on your list. But you're always going to have attrition at each level. For example 10,000 IG followers may convert to 400 people on your email list and maybe 10 of those will buy something you sell (your results may vary).
Or I could have just said: Selling online is virtually always harder than it seems. Best of luck.