According to the User Guide for the product it seems like it is only made for use with Dell laptops. There is absolutely no mention of any other brands of computers in the user guide. Plus the USB-C ports on this adapter only support the USB protocol (Thunderbolt is not supported).
https://downloads.dell.com/manuals/all-products/esuprt_electronics/esuprt_usb_accessories/dell-usbc-mobile-adapter-da300_user%27s-guide_en-us.pdf
You should get a device that is meant to work with Macs. OWC is a well respected vendor supplying accessories & peripherals for Macs for over 20 years.
https://eshop.macsales.com
Edit: Also, you must have the 2018+ model since the 2017 MBAir has no USB-C ports. Please make sure to note the correct model when posting as it can make a huge difference. You can get the exact model of the Mac by clicking the Apple menu and selecting "About This Mac".