LDT file type

what “mime type” have you inserted in the administration form when you have added the new file type ? Is there any test page you have and i can use to see what happens ?

What type of web server are you using (apache, nginx, iis) ?

Often “download” or “view” are related to server’s and/or browser’s configurations …

i’m marking this topic as “not a support question” because the plugin doesn’t alter the way WordPress and the webserver send files back to the user

upgrade to plugin’s latest version and follow instructions givene here : https://www.ads-software.com/support/topic/cant-upload-excel-documents/#post-9078481