Hi Jack,
What you describe sounds like the Reader interface. Is this what you see?
If you're signed in, you'll see your name in blue in the upper-right corner. If you do see your name, please sign out, and then sign back in.
Now you said that you uploaded a file: Did you use the Store Files option on the column referenced above? When you upload files, they are stored in your online account at https://cloud.acrobat.com.
And, you can also access ExportPDF from that same URL. (ExportPDF is available both from within Reader, and via the web--it's the same thing, just different ways of accessing it.)
Please try signing in directly to https://cloud.acrobat.com. You'll find your uploaded file on the Files tab, and you can click ExportPDF to do your conversions. One stop shopping!
Best,
Sara