You cannot vote on mobile devices.
Check here for more information: https://forums.technicpack.net/topic/323499-bacon-pixels-1122-200-slots-dedicated-host-pixelmon-reforged-vote-rewards-poke-hunt-player-driven-economy/
You will need the Technic Launcher, found here: https://www.technicpack.net/download
You will also need the specific modpack, found here: https://www.technicpack.net/modpack/bacon-pixels.1489408
The server is already installed in the modpack, so launch it and join on in.