Any of the paid versions of Zoom now feature free captioning.  Make sure you or your facilitator have downloaded the latest Zoom update.  When you turn on Live Transcribe the captions should appear across the BOTTOM of the screen (white lettering against black background), and is very readable.  You can click the arrow next to "CC" on the bottom of the screen and adjust captioning settings (e..g., you can increase the size of the lettering).  The large white rectangular box you may be referring to (on the right side of the screen) is if you have clicked "show transcription" and you will see a scrolling record of the transcription; plus you can also save that transcription.