Not being able to replace a world on a realm

I play on bedrock edition and I decided since I had a world where I play with my friends, I thought maybe I should buy realms, so when Idecided to buy realms it automatically made a world for me, luckily I could replace it with a world that I already had saved, which Is what I thought until I kept getting repetitive error messages. I’m not the only person with this problem, many others around the world are having similar issues with this, tutorials on fixing don’t seem to be reliable either. If there is a way to fix this please someone tell me, I feel like I wasted money on this.