Browser Support
WebMAP's 5 applications are designed as any other standard Angular 5 application. You can verify browser support list on the Angular website at Browser support
Support on Internet Explorer and Older browsers
Angular is designed to run with the latest versions of major browsers, but if you insist in using an older version of Internet Explorer or FireFox there some little tweaks that you need to perform first in order the application runs as expected.
There some JavaScript libraries that are required to support most of the Angular's platform in older browsers. Those are called Polyfills.
You are going to need enable those polyfills in order to make your WebMap's 5 application available for older browsers like IE11. Please follow this instructions.