When I choose to combine PDF's it only lets me save it as a portfolio, I don't want to do this, no one else can open these. I want to combine several PDF's and save it as one single PDF's there's no option in the drop down for save as a PDF it automatical

When I'm in Acrobat adobe DC, and I choose the combine tool, I choose the files I want to combine and then adobe automatically saves this as a Portfolio.  I don't want it as a portfolio because no one else can open it on the other end. I want to combine these files and save them so I can upload them as one PDF, I cannot find a setting in adobe acrobat DC to change this. Please help!!!!!!