Using the cloud

I had an old mac mini with 512gb of storage. Now I have a newer Mac mini with only 129 gb. I have 1.51 gb of space left which leaves me crippled. The old mini ran flawlessly since 2011. I used it primarily as a jukebox wired into my home stereo system and the photos app, both of which take up 244 gb of storage. I also use the cloud with 2 tb of space an external hard drive with 3tb of space and another hard drive with 500gb of space. I'm lost with the system, I cannot do anything. I have set up all the optimization settings, I just got the mini back from a shop as I previously froze it up before understanding it's limitations

Now after less than 24 hours of attempting to use it, I'm near freeze it up again. I'm lost with all of this. Apple has geared everything towards the iphone and has thrown the hobbyists under the bus. I've been working on all of this for a combined 4 months. I know my mac better than some gurus, but cannot figure out how to operate my music or photo systems. My question? I think I should dump the icloud and work from one of my two back ups. what say you?