rxjs has no exported member concatLatestFrom code example

Example 1: rxjs/Observable"' has no exported member 'Observable'

It looks like rxjs-compat is missing. 
just do 
> npm i rxjs-compat 
right after 
> npm install 
then do 
> ng serve -o

Example 2: Namespace 'google.maps' has no exported member 'MarkerChangeOptionEventNames'

// It seems, that Angular 11 does not work properly in combination with 
// @agm/core 3.0.0-beta.0 (newest version). Try to downgrade @agm/core to the previous 
// version 1.1.0.

"dependencies": {
    "@agm/core": "^1.1.0"
}

// (run npm install after changing the agm version)