Hi, @ELIAS NTOKOS ,
More detailed information about your setup and goal will help us to provide more specific suggestions. And only for the error message, have a check on the Assembly and try to close & reopen the VS to set up the connection again. Make sure you have installed the SharePoint Online components SDK.
Reference:https://social.msdn.microsoft.com/Forums/vstudio/en-US/557cd871-b93f-4e55-8e75-a5d7b1a65adf/getting-error-when-try-to-connect-to-sharepoint-on-cloud-from-ssis-vs?forum=sqlintegrationservices
If the answer is helpful, please click Accept Answer and upvote it.
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.