@Gerryatric seems you are using a not official docker.
Seems we don't know what PHP version are you running, if the PHP is old like PHP 7.4 UVdesk can have issue and you can run also in security issue as the PHP is no more supported..
What I can suggest is to install UVdesk from an official repo.
You can download the zip already compiled here.
Then you can try to run the install wizard by loading the address of the public UVdesk folder. During the wizard you should see what version of PHP are you running.
You can check currently supported PHP version here: https://www.php.net/supported-versions.php
Personally I use PHP 8.3