ITFlow is very light on resources for the most part. A modern virtual CPU, 2 GB of RAM and 10 GB disk is plenty. Before we had Jenkins and the develop branch, I used to run a PR Review instance on the oracle free tier. A fraction (1/8?) of a CPU core & 1 GB RAM running multiple ITFlow dev sites just fine.
Even if you're buying a physical server just for ITFlow (which is overkill unless it's a lil micropc), set up something like Proxmox or Hyper-V and run ITFlow as a VM/LCX. It makes your life easier in many ways.