Trouble with setup even with soap installed

Hello,
I have php soap installed on my server (according to my php.info file and it is enabled and running.

I am still having issues with this plugin after activating it. I have also tried deactivating the plugin, removing it from the plugins directory, and adding it back. Each time, when I save the marketo settings I entered, the screen goes blank and I am not able to add any feeds or edit the settings I have.

In addition to that, now when I deactivate the plugin and try to re-activate it, the settings page does not show my settings anymore, it always stays blank.

Any help would be greatly appreciated.

Thanks!

https://www.ads-software.com/plugins/marketo/