Adding a button to wp/aution plugin

I got an auction theme (adifier) and i’m trying to add a button to a specific ads category.

Tried a few codes but none seem to work, probably i don’t know how to alter it properly. I got the category 3D Design where users should download the files that are uploaded from account page (where I should add another button with upload (I got I plugin with the upload button but don’t know how to add it on the account page) ). Thanks in advance for any kind of help!