非web目录的mime.type

I'm hoping someone has some experience with this issue and has some advice or thoughts. I have a download directory outside the apache2 webroot. Lert's call it: /var/downloads/ This is where we keep all of our PDFs, .docx and .xlsx files.

(The webroot is /var/www/html/)

PDFs download OK, but excel and word files become corrupt and cannot be opened after download. I think this is a mime-type issue, but I don't know to to resolve it. I've tried AddType in /var/downloads/.htaccess to no avail. Honestly, I'm not even sure a .htaccess file would even work in a non-apache directory.

I should also say that .xlsx files download and open w/o issue when served from the webroot.

Is there anyway to resolve this? Thank you for your time.

Ubuntu 16.04; Apache 2.4; PHP 7.2