You can't open a Microsoft SharePoint list in Datasheet view.
This behavior is by design.
This issue occurs if one or more of the following conditions are true:
A version of Microsoft Office that includes the datasheet component isn’t installed on the computer.
Note The datasheet component isn’t available in 64-bit versions of Office.
The Web browser doesn't support ActiveX controls.
Support for ActiveX controls is disabled.
To work around the issue, use one of the following methods:
Use another type of SharePoint view, for example, the Quick Edit view that was introduced in SharePoint 2013. The Quick Edit view uses HTML5 to present the view. It doesn’t depend on ActiveX controls.
Use the Open with Access option to create a new Microsoft Access database that contains a linked table to the SharePoint list. Then you can edit the list data in Access.
Create a linked table in Access by using the SharePoint List command in the Import & Link group on the External Data tab.