In this step, you should have downloaded each of the files (FIREAC - discord-screenshot - oxmysql).
*Usually, servers with an ESX base have oxmysql for their database, and there is no need to reinstall it.*
Now, add both to the resources in your server.cfg.
Note that in discord-screenshot, which you downloaded, there is also screenshot-basic, meaning the discord-screenshot contains 2 resources.