PHP 7.3 reached end of life on 06 Dec 2021 and is no longer being updated. It's strongly recommended to upgrade to the latest version as soon as possible. You can read the official PHP migration guide here.
Installing PHP 7.3 on Server 2022
Prerequisites
Windows Server 2022 installed and updated
Administrative access to the server
Internet connection for downloading PHP
IIS (Internet Information Services) role installed
Installation
Download PHP 7.3 from the official PHP website
Extract the downloaded ZIP file to a folder (e.g., C:\PHP7.3)
Copy php.ini-production to php.ini in the same folder
Open IIS Manager and navigate to the server node
Open Handler Mappings
Click "Add Module Mapping" in the Actions pane
Set the following values:
Request path: *.php
Module: FastCgiModule
Executable: C:\PHP7.3\php-cgi.exe
Name: PHP 7.3
Click OK and then click Yes to create a FastCGI application
Add C:\PHP7.3 to the system's PATH environment variable
Verification
Create a new file named phpinfo.php in the web root directory (usually C:\inetpub\wwwroot)
Add the following content to phpinfo.php:
<?php phpinfo(); ?>
Open a web browser and navigate to http://localhost/phpinfo.php
Verify that the PHP info page is displayed, showing PHP version 7.3
Check that the installed extensions and configurations are correct