Build Simple Login in PHP - unable to get working

Good day, I am trying to enable a legacy PHP program/solution that currently uses Microsoft Active Directory to authenticate from. My request is to convert/migrate this application to utilize OKTA as the authentication method. I am open to any and all formats, and have a pretty much a free hand to do what I wish to get this working.

In the developers web site, I came across this example, which I am unable to get working even without altering any of the code from GitHub

and downloaded from

when I attempt to run this example I get this result.

[prsuser@localhost ~]$ php -S 192.168.1.238:8080 -t public
PHP 5.4.45 Development Server started at Mon Dec 16 11:20:41 2019
Listening on http://192.168.1.238:8080
Document root is /home/prsuser/public
Press Ctrl-C to quit.
[Mon Dec 16 11:20:44 2019] PHP Fatal error: Class ‘Src\Services\OktaApiService’ not found in /home/prsuser/public/index.php on line 7
[Mon Dec 16 11:20:44 2019] 192.168.1.180:26408 [500]: /public - Class ‘Src\Services\OktaApiService’ not found in /home/prsuser/public/index.php on line 7

As you can se the server side, abends with this class not found.

So far I am unable to understand why. Certainly this example code is fine, I must be doing something wrong but cannot see why – I wanted this to work as a starting point.

If anyone else has a better example or method I maybe able to use I would certainly love to hear it.

Thank you
Charles