You can import data from Microsoft Excel to a data tree in Assemble.
To import a data tree, do the following:
From the Project Dashboard, select Edit Project at the top, right corner of the page.
The Project Settings dialog appears.

Select Manage Data Trees.
The Manage Data Trees dialog appears.

In the Data Trees box, select a data tree for the imported content from the dropdown list.
Select Import at the bottom of the dialog.
Browse to the where the data is located that you want to import.
Select a file to import, then select Open.
The Manage Data Trees dialog appears.
Select Done.
If you receive the error: "The file is in an invalid format...", check the following in the file:
Once these items have been confirmed, retry the import.