Depends on what kind of music you make and what you are trying to accomplish. If I was making music that people might actually be interested in listening to and buying, with lyrics, vocals, and all that, I wouldn’t go for a label or a stock site at all these days, I’d self-promote and DIY everything - look into advertising on youtube for example, cheap as hell. What can a label really do for you these days that you can’t setup yourself or hire an agent to do? Recording? Costs 1/100th of what it used to. Promotion? Has moved heavily away from the radio onto the internet. They can’t do a whole lot besides advancing you money and putting you into debt. Remember, record labels are playing the same game as everyone else, they have to recoup the money lost on supporting their less successful artists with money from the successful ones, so a record deal is by no means any kind of measure of success these days. I know some bands and all they do is tour to pay off the money they owe their labels. But I’m sure some labels are better than others. If people want to make money as musicians these days, they really need to focus on the business side of it, not just the creative, because the days of free money and free breaks with low competition are gone.
Stock sites like AJ are really more for generic/utility music - almost no one is buying music here to listen to and enjoy, it’s all for utility, and it’s not a great business model for the musician - usually a huge emphasis on quantity and a bit of a grind. This is fine if that’s the kind of music you want to make, otherwise I’d try Bandcamp or a similar site, or build your own website and sell your music directly to people, then you are making real money, not just percentages.
Cinematic music? Meh, probably not here, probably not in bulk anyway, better to try and join or start a production house or library, still no PRO support here, or try to score something. The most important thing in music is the most important thing in all business; brand recognition. The more people know who you are and respect you, the more you can charge for your goods and services. The second most important thing is promotion and marketing. No one is going to buy your product if no one knows you exist. The third most important thing is networking and connections. You can’t get free or cheap exposure without securing some connections/synergistic relationships with people. Somewhere, many pages down the line, you get to the actual importance of the product itself, in this case music.
If that all sounds a bit pessimistic it is, but again I believe business side of things > music side of things, in regards to making money. Otherwise if it’s just about making music, then it doesn’t really matter much, just do it because you enjoy it, or maybe sign with a label and see what happens…but the business side, yeah, you can do it yourself these days if you really want to, because the internet exists. Labels, stock music sites, these all exist to make money off of the convenience of the musician, it’s very convenient to pay other people to work the business side for you, but try and apply this model to any other business besides entertainment and maybe sports, and I don’t think you’ll find too many success stories.