Things for you to try if you use a windows computer and haven't tried these already: Try opening the attachment in a different browser than Edge (hopefully you have a second browser on your computer). You can do this by copying the link (if there is one) of the attachment and pasting it in the different browser.
You could also try saving the attachment to your downloads before trying to open it. Then, go to your downloads and try opening it from a program that can read those files - for example if it is a pdf file then open it with adobe reader or similar. If you right click on the file in downloads, there will be a dropdown list that includes an option "open with". The program you want might show up there. Otherwise, open the program itself and go to file, open, and then select the downloads folder and the file you want.