The error "Can't find plugin "sdkEngineplugin.dll" error" usually occurs when Alteryx is unable to find the SDK Engine Plugin, which is required for connecting to SharePoint. To resolve this issue, you can try the following steps:
Verify that you have the correct version of Alteryx Designer installed. The SharePoint Connector requires Alteryx Designer version 2020.3 or later.
Check the Alteryx installation directory for the "sdkEnginePlugin.dll" file. If the file is missing, you can download and install the latest version of Alteryx Designer from the Alteryx website.
If you still cannot find the "sdkEnginePlugin.dll" file, try repairing your Alteryx installation. To do this, go to Control Panel > Programs and Features, right-click on Alteryx Designer, and select Repair.
If the repair option is not available, you can try uninstalling and reinstalling Alteryx Designer.
If you still have trouble resolving the issue, you can try reaching out to Alteryx Support for further assistance.