Attaching a table or document

How can I attach a file? I see the tab below, but the Field for the file name is grayed out and I am unable to add anything.

It looks as though you can only add a file from the PC, not the mobile app.

This is an attempt to add table 4 from admin01 discussion on Alliance Mine wars.

Mine Wars Table 4.png (13.42 KiB) Viewed 2276 times

Yea, it works! For you Skugg.