The MRCL server is meant to be fully playable just by joining with your Minecraft launcher and accepting the Resource Pack.
However, there are various things you can do in order to improve your experience - both lag wise, and visual wise.
We've uploaded a modpack with allowed and recommended mods on Modrinth: https://modrinth.com/modpack/mrcl. You will need to use the Modrinth launcher to install it.
This includes: