Server Requeriments

I need install server, but not know how requeriments its best for that.
Pretend use with 15 users simultaneous.
Thanks

Depends on number of devices and message volume.

Thanks , 1 User , 15 Devices. I think pay a VPS with initial 2GB ram , 80GB SSD . But if server need more resources, please, tell me.

That should be enough.

Thank you .