Looks like you can download the driver from this page -
https://www.tp-link.com/us/support/d.../ub400/#Driver
or use this direct link -
https://static.tp-link.com/2018/2018...400_Driver.zip
Here is the "Common problems" page from the FAQ if you get stuck -
https://www.tp-link.com/us/support/faq/2316/