Social Media Post Scheduler with a generous free tier?

I am looking for a social media post scheduling app with a generous free tier. Something that I can grow my SaaS business with. I saw later.com had a great platform but unfortunately I cannot get it to connect to my Facebook accounts that are located in my business manager (even though I am an admin on the page). It's been frustrating to say the least. I'm just looking for something with Facebook, IG and Twitter integration. What do you all use?