Insufficient iCloud+ space for iPhone backup and app storage

I have issues with space please. I recently got 50GB of iCloud+ but I’m not being able to move my files into it. My phone is not backing up, my apps are not opening because I don’t have RAM space any more. The 64GB is almost full. What do I do?

[Re-Titled by Moderator]

Original Title: Using my iCloud+ space