Salesforce and SharePoint integration can be done using the below two components. File Connect, Lightning Connect

tenthplanet blog salesforce How to establish a connection between SharePoint and Salesforce

In Salesforce, Go to Setup-> Security Controls ->Auth. Providers. Click New

tenthplanet blog salesforce Authenticate the User in Salesforce to access SharePoint files

The user must be authenticated to schedule the apex class and also to view the SharePoint files under the tab chatter.