You cannot add EAs directly from mobile trading platforms, but you can certainly view the activities of your EAs from mobile trading platforms.
In order to run EAs(expert advisers), it is necessary to run a Desktop version of MT4 or MT5 and add your EAs there. It is also necessary to keep them running without being closed.
Then, you can monitor the activities of your EAs from mobile trading platform.
In this case, your EAs are running on the MT4 or MT5 Desktop, but not not on the mobile platform, thus you can not modify the settings of your EAs from mobile phones.