You can base64 encode your file and use that encoded string as variable in your microflow, where you let a user download the template (I'm guessing thats the use case). Go to Base64 Encode and Decode - Online and encode your Excel file.
ACT_Template_Download would look something like this
1. Create variable 'String' and paste the base64 endoded string of your filedocument in there
2. Create filedocument (or specialization) to be downloaded, with a proper filename and extension
3. Java action from CommunityCommons.Decode64ToFile and pass your parameters
4. Download filedocument
Hope this helps you to find a workable solution!