Open Edge (blue 'e'), then log-in to your Lambslist account.
Next, click on the 3 dots in the upper right-hand corner, then select Open with Internet Explorer
This open IE 11 on your computer, proceed to Lambslist and log-in as you would normally.
Note: you may want to right-click on the Internet Explorer icon, in the taskbar at the bottom of the display, and select 'Pin to taskbar'. This will keep the Internet Explorer available on the task bar so you won't have to access it through Edge.