button for Importing meeting registrants by CSV upload is missing

Welcome to the Zoom Community, @c4vets.

Please see the Prerequisites section of this Zoom Support article:

https://support.zoom.us/hc/en-us/articles/11830867843213-Importing-meeting-registrants-by-CSV-upload

There it states these three important requirements:

• Licensed host
• The meeting ID must be generated automatically instead of using your PMI
• The meeting cannot be a No Fixed Time recurring meeting 

I'm guessing your situation is one or more of the following:

• You are a Basic account
• You are using your PMI for the meeting ID
• You have specified a recurring meeting with "No Fixed Time" as the recurrence.

You can likely fix the first two, but if you want to "gather together whenever" instead of a fixed time interval, it's not going to work.