How do I include flex-layout?

1. Change version of flex-layout compatible with Angular 8. update angular.json

"@angular/flex-layout": "^8.0.0-beta.27"

2. install this update

npm install

To avoid this error update tsconfig.json (Not recommended)

"compilerOptions": {
   "skipLibCheck":true
}

Try to add tslib in dependencies

npm install --save tslib

Edit

If you are using Angular v8 then use v8 for flex-layout cause v9 need Angular v9.

It's because you are on Angular 8 but the library required Angular 9. In your package.json use this version : "@angular/flex-layout": "^8.0.0-beta.27"