It's really up to Enjin, but at the moment, PE servers are no where near as popular as PC servers and it really isn't worth their time to develop something for such a small amount of users. However, if you want an automated donation system, @Falk ported the BuyCraft Bukkit plugin to PocketMine (found here). It isn't supported by BuyCraft itself and has to be set up a certain way with the BuyCraft website, but overall it should work very similarly to the Bukkit version.
