1. Set a port to use in config.yml, server hosts may provide you a specific port to use
2. Use your server ip/votifier port and public key on the voting site. Tokens will also work in more recent versions if enabled.
3. If using VotingPlugin, follow VotingPlugin guides for any proxy/rewards setups. Otherwise setup forwarding of votes in VotifierPlus

Other guides:  
https://mintservers.com/knowledgebase/set-up-votifier-on-minecraft-server  
https://snownode.com/clients/knowledgebase/37/How-to-Set-Up-Votifier-.html  
https://scalacube.com/help/gameservers/minecraft/how-to-setup-minecraft-votifier  
https://help.pebblehost.com/en/minecraft/how-to-setup-votifier  
https://docs.frac.gg/games/minecraft/plugins/votifier  
https://server.nitrado.net/en-GB/guides/votifier-plugin-minecraft-voting-guide  
https://www.minecraft-hosting.pro/article/15-votifier-installation  
https://help.pebblehost.com/en/minecraft/how-to-setup-votifier-with-a-bungeecord-network  
https://shockbyte.com/help/knowledgebase/articles/how-to-set-up-votifier-to-allow-voting