Currently, the theme is using TGM-Plugin-Activation to require installation and activation of the required plugin, Unfortunately, TGM-Plugin-Activation is not compatible with WP multisite, so you need to install the required plugins manually.
We're sorry for the inconvenience, but we'll try to improve it as soon as possible.
If you have difficulty installing themes with Multisite, please open a ticket here for support - https://help.chisnghiax.com/