Hi @Haze ,
We are sorry you're facing this issue. Have you tried updating your PHP version (7.4) to the latest version?
Make sure your PHP version is updated before trying to install an extension. To update the PHP version, Go to your app in the Azure portal and click on the Settings button. From the Settings blade, select Application Settings and choose the new PHP version.Click the Save button at the top of the Application settings blade. This can also be done through CLI and powershell as shown in this documentation.
Also, you can double-check to see if you already have SOAP installed by using this command: php -i | grep -i soap
. If it is not installed, trying using this command sudo apt-get install php7.4-soap
and then restart your server. You can also see this related Stack Overflow thread.
Hope that helps. Please let us know if you have further questions
-Grace