I'm fairly new to this world, having just taken over my company's (casual games company) social media department with literally zero experience, so there may be other ways to run advertisements on FB, but for us, we basically 'boost' our posts, which turns them into advertisements using the Meta Business Suite. We initially create our posts using ContentStudio, and then when we boost them through MBS, there are several settings in there to sort of choose your audience & goals, but for pricing, we decide how long to 'boost' the post for, then put in how much or budget is for that post. So if we use $100 for a 7-day boost, it will give you an estimate of accounts reached, which in this case is like 2.9K - 8.4K. The reach varies, of course, based on the type of post, number of days & budget. Sorry that I don't have specific numbers, and I'm sure there's a completely different way to advertise on FB, but that's how we do it. More on reddit.com

Check out Andrew Southworth on YouTube. He does some really great videos on advertising music through Facebook and other platforms. And despite the clickbaity video titles the videos are just him showing what h does, and his results and showing you how to do it. Basically you want to set up a Facebook pixel on your landing page so Facebook can target the ads at those that actually click through to your Spotify. I released an album a couple of weeks ago... first thing released under my new artist name so I was basically starting from scratch. I've managed to get about 600 plays and 25 followers on Spotify for about £70 of Facebook ads by following his "Facebook conversion campaign" advice. May seem like small numbers, but growth is always going to be slow to begin with! 646 people clicked through on my Facebook ad, and of those 359 clicked through to Spotify. His vids would probably help you create a plan for when your EP drops. More on reddit.com