As the title states, I've correctly installed the plugins as well as uMod, double checked and triple checked after a couple hours of fiddling and doing a couple fresh installs, I can now see this is completely an error with the compiler not compiling the plugins, so even though the plugins are in /oxide/plugins they aren't showing. All oxide commands work, but compiler won't start. I've seen a lot of posts referring to this happening when there's not enough ram / disk space, and whenever the compiler starts the server is only consuming 1.2-6 GB / ram out of 16 GB and using the df command shows the disk has only been used 15% of it's total capacity. So, that's definitely not it. I'm really left scratching my head here, I've done everything I can think of and literally everything I find online isn't really related.

Any help would be greatly appreciated, please. 

Yeah nvm, just deleted Compiler and ran server and I can see the plugins loaded, and it created config files. Will update later if I slam my face into another wall.