Ensure that the account used to connect to the SharePoint Online App Catalog does NOT use multi-factor authentication. If you upload the SharePoint Online Connector App Package using multi-factor authentication, the upload will fail.
The installer, which deploys the app package, needs to be run from a machine where TLS 1.2 is enabled.
To install the SharePoint Online Connector to a specific SharePoint Web, you need to upload the App Package to the SharePoint Online App Catalog, which makes it available to the Web for installation.
To upload the SharePoint Online Connector App Package, enter the necessary deployment settings, and then click Next.
Connector Web URL: The URL to the SharePoint Online Connector Web
App Catalog URL: The URL to the SharePoint Online App Catalog
Client ID: The Client ID that was generated during section 5.1.1
SharePoint Online Username: Used to connect to SharePoint Online
SharePoint Online Password: Used to connect to SharePoint Online
Click Next. The App Package will be uploaded to the SharePoint Online App Catalog you specified above.