Hey, professional composer/producer here. I thought I'd give you some honest feedback from one of your target users. These are my more or less unfiltered thoughts as I scroll down the page. Apologies in advance for the bluntness:

Man, that iPhone photo on the right is a little blurry and way too big.

"The smart way to share music privately." Me and everyone I know uses Dropbox. The majority of us pay for Dropbox accounts that allow you to disable downloads, so it's as private and secure as I need it to be. Beyond that, there are a number of more specific competing services already -- for example, ReelCrafter allows me (a film composer) to host video and audio for less than $17/month, with insights. What are you offering that I don't already have or can't get elsewhere, quite possibly for less?

The "Get Started" button is above "What is SongBox?" Why would I get started when I don't even know what it is?

Profile Page: Feels like social media. That in and of itself kinda feels like friction.

Insights: This is nice. I definitely like this, because I do sometimes get annoyed when I send music to someone and don't hear back, and it'd be nice to know if they listened. This solves a real problem for me.

"Stop Wondering If They Listened." Yup, there it is. I like it.

The photo below this section is unnecessarily huge. This page feels weirdly like it has too much text and too many photos at the same time. Not sure how to solve it but even though the design is clean, it's a little fatiguing.

"What SongBox Users Say" Speaking of too much text, all of these are too long and there's no way I'm reading all of them. Either roll them all up into a "Testimonials" page and link me to it, or choose the biggest name you have a testimonial from and feature it higher up on the page -- and keep it short.

Pricing. In a vacuum, this pricing is nice. But it's one more cloud storage service I'm paying for, and in that light it's suddenly way too expensive for the higher tiers. Highest I'd personally go for Pro is $20/month and that's still pushing it.

"How Does It Work?" This section should be much higher.

"Don't Worry About Sharing Your Music." This page now feels redundant and way too long. Axe this section and merge the unique info elsewhere. Ditto for "Share your tracks anywhere."

All in all: The front page could be condensed to half or even less than half of its current size/info dump. The service seems solid but enough for me to try the free version, which if I'm honest will probably result in me forgetting about it -- paying something no matter what would at least put in my mind a sense of needing to use it.

I know you say in your post that your pricing was wrong, but if it were me (with the little info I currently have -- who knows, maybe you tried this and it was wrong) I'd do the following:
-Lose the "Starter" as it is and "Semi Pro" tiers.
-Retitle "Hobby" to "Starter" or something similar (though I don't love that -- I think you should entirely focus on professionals, i.e. people willing to pay money long-term; anyone needing these features already has a free Dropbox/Google Drive account that already works just fine, so name your tiers appropriately).
-Now you have two tiers (easy, simple, doesn't require too much thought). Allow both to use any file type (that's a frustrating and arbitrary limitation). Price the former Hobby-now-Starter-or-whatever-you-call-it tier at something stupid low, like $2/month. Make Pro $15 month or so.
-Allow a 30 day free trial with Pro features -- again, no credit card required.
-If someone with a Hobby-or-whatever account tries to cancel, allow them to disable downloading for an extra $1 per month -- a hidden "middle" tier. I guarantee you that lack of disabling downloading will be the #1 reason people cancel their account.

This has the potential to be great and you've clearly put a ton of work into it. Wish you the best and hope this succeeds.