I notice you're asking about a "photon launcher" in Phasmophobia, but there is no such item or feature in the official game. Phasmophobia is a ghost-hunting investigation game that uses equipment like EMF readers, thermometers, spirit boxes, and UV lights—not weapons or launchers.
Users frequently encounter barriers when using this third-party tool: photon launcher phasmophobia download
And for real ghost-hunting firepower? Use the Tier III Salt or Tier III Incense (aka the “Molly”). Those are the closest things to “weapons” in the current progression update. I notice you're asking about a "photon launcher"
Furthermore, Kinetic Games actively bans in waves. Even if a cheat works today, a silent update tomorrow can flag your account. Use the Tier III Salt or Tier III
If you have obtained a version of the game that requires the Photon Launcher, the setup generally involves the following steps: