Cannot export data

We have been using the CFDB plug in for several years to collect reservation requests for dinners we host on our farm. It has worked very well for us until recently. I just now discovered that updates for the plug in through WordPress are no longer supported. Unfortunately, we received reservation requests on Saturday when we opened up for the next three months of our season and I am now unable to export those requests into an excel file to process them. There was an error message with the confirmation message, which resulted in people submitting multiple times. As a result, we have nearly 18,000 entries in the database that need to be cleaned up, duplicates deleted and such, and then use the remaining data to process reservations. There is no way for us to do this directly from the database. We need to export it, but when I try to export any amount of the data, from a few records to all 17,500+, I get an error message saying This site is experiencing technical difficulties.

Can you help me find a solution to exporting the data? In looking at the instructions for reinstalling the plug-in from GitHub, it looks like I have to uninstall the plugin first, which would certainly result in a loss of data, correct?

The page I need help with: [log in to see the link]