Adding Slido to a Google Slide Show with PPTX extension not owned by me using my paid Slido account

I have access to an existing slide show created in PPTX and uploaded to Google Slides.  I do not believe it has been converted to native Google Slides.  I am not the PPTX or Google Slide Show version owner.  I have been asked to add a word cloud or poll to one of the slides.  I am an editor on the slide show and I have a paid Slido account but I cannot get the Slido extension to show on the slide show even though I am logged in.  How can I use my paid account with an existing slide show not owned by me?  Earlier this week I had to create my own Google Slide Show, copy all of the slides over, and then I could use Slido with the presentation.  Surely there is an easier way?