Type-C charging requires a power adapter that supports the USB-PD (Power Delivery) protocol, you can’t just charge your laptop with your phone’s charger. The upside is you can charge your phone with a PD charger, so that charger can be a common charger for all your Type-C devices.

Unfortunately, it seems that your laptop does not support it https://www.reddit.com/r/System76/comments/8i1j7m/galago_pro_can_you_charge_it_over_usb_c/