fed up with lack of space on C Drive...what am I doing wrong?

I am trying to do everything right. Vigilance, using auslogics and bitreplica, as well as duplicate file finder, however almost every day, my hardrive fills up, and I can barely get a file to open, due to lack of memory. I have done everything that I know, to try to have all files saved to onedrive, or icloud, but it doesn't seem to make any difference! The computer jams up, because it has reached maximum capacity! Why does this happen, when I am saving files to onedrive (cloud storage). I'm really about ready to chuck this new laptop into the rubbish bin. But.....all available 'new' laptops appear to only have minimal hard drive space. The retailer told me to save my files to the cloud, which is what I am doing, so why does the C drive continually fill up. I move stuff to an external hard drive, in an attempt to free up space, but as soon as bitreplica runs, I'm back to square one. I'm so frustrated, as it takes several minutes just to open a word document. Please please please, can you give me some guidance / direction as to what it is that I am doing wrong. Regards, Kerry