XML PHP Extension

Hi, I have just installed Mailpoet and I am getting the error saying I have not installed the XML PHP extension. I have checked the documentation and believe it is installed.

I am running Mailpoet version 3.60.2 on WordPress 5.6.2. Running on NGINX 1.14.2 which is running on a Raspberry Pi OS 2021-01-11 which is built on Debian Buster

I am running PHP 7.4. The documentation link Mailpoet provides is:
https://www.php.net/manual/en/xml.installation.php
and states it should be enabled by default. There is a note for Ubuntu users which says it may not be and to run
“sudo apt-get install php-xml”
and restart the server. I have done this and it states:
php-xml is already the newest version (2:8.0+81+0~20210223.34+debian10~1.gbpf52eb0)

But I still get the error. Can anyone help? Thanks