To give a player access to use a warp (I am assuming you are using Essentials), you have to give the player access to the permission.
Examples:
Luckperms:
/lp group <group name> permission set essentials.warps.<warp name>
PermissionsEx:
/pex group <group name> add essentials.warps.<warp name>
Group Manager:
/mangaddp <group name> essentials.warps.<warp name>
https://youtu.be/FU_tK-zYYb4