iCloud and the folder Mobile Documents are taking up too much storage space on my macbook hard drive.

With iCloud and iPhone backups taking half of my macbook pro hard disc space, I want another solution. Microsoft OneDrive is not supported on my 2011 macbook running High Sierra OS, so I cannot use it. Is there another cloud service anyone knows about that will allow me to store data off my macbook, and also allow me to backup my iPhone, without creating storage problems on my macbook hard disc? Isn't that what cloud storage is supposed to do anyway? Apple's iCloud seems a joke if they need to put your cloud storage on your local drive as well! All I care about is my Logic Pro Projects, which I store on an external hard drive, but I also want a second storage for them in a cloud. And of course, I want to backup by iPhone, but not when that creates a 149GB Mobile Documents folder in my macbook!