What you need for CRx:

Use the quake remaster client from steam or go to the clients page, download one of the community maintained clients and add your registered Quake 1 pak0.pak and/or pak1.pak files to the id1 folder.
Bring down the console and connect. example: connect denver.crxquake.com:26000

What you need for Bloodrailz:

Go to the bloodrails page to download the bloodrails client, add your registered Quake 1 pak0.pak and/or pak1.pak files to the id1 folder.
Use the game menu to connect

FYI: when you buy Quake 1 off steam, you can get the pak files from C:\Program Files (x86)\Steam\steamapps\common\Quake\id1

Join the Flux Dojo Discord - Bloodrails discord