The setup section links to https://minecraft.curseforge.com/projects/requiem

Clicking download downloads "Dissolution-1.12.2-0.3.9" - which then says it's the beta forge version and new development is happening on fabric. How do I download the fabric version? I'm using MultiMC

Aah, I needed to click the "Files" tab and download the proper version. The "Download" link that curseforge puts in the top right corner seems to be nearly always wrong....

Ah yes, curseforge being garbage as usual. Glad you found it !