By default, Microsoft Edge is the newest default browser in Windows for all sites and web portals. If a legacy website or web portal needs Internet Explorer to work, you can enable IE compatible mode in Edge to view the site, and the steps below show you how to do that.
To enable IE mode, open the new Microsoft Edge, go to Settings and more > Settings.

When the Settings page opens, go to Default browser. Internet Explorer compatibility select to Allow all sites to be reloaded in Internet Explorer mode as highlighted below.

Or you can simply type the URL below in Edge browser to go directly to the Default browser settings.
edge://settings/defaultBrowser
When you select Allow, you’ll be prompted to reload Edge for the changes to apply. Click the Restart button.

When browsing in Microsoft Edge, if a site requires Internet Explorer for compatibility, you can choose to reload it in Internet Explorer mode.
You can also manually add pages that are built on IE standard to automatically load in IE compatible more for 30 days. Click the Add button to add a site or page to load in IE mode by default.

Type the site URL or page link that you want to load by default in IE mode.

When you want to reload a page in IE mode, simply select the three dots at the top right of the toolbar and scroll down to Reload in Internet Explorer mode.

That should do it!