Error downloading world in realms

I started a realm in order to pull my working world from the application so that I could save it externally, mainly to play on my tablet. However, every device I have tried to download the world to, an error message pops up that says I do not have enough space, please remove items to free up space. My world isnt more than 300mb and ALL of my devices have more than plenty of space. I now have spent my free trial waiting on a response which lead me here. Please advise what I can do in order not to lose my world I spent time on. Thank you.