I think by power they means hardware (the two are correlated), so, it depends on many things but we can start from:
Server Specifications
Requirement Minimum Recommended RAM 1 GB (with swap) 2 GB+ CPU 1 core 2+ cores Disk 10 GB 20 GB+ OS 64-bit Linux Ubuntu LTS
From https://github.com/discourse/discourse/blob/main/docs/INSTALL-cloud.md
A recommended specs server start around 5€ on several providers, not counting domain/email/etc…
Way cheaper for CDCK to host their own forums on their infrastructure, I suppose 