Plug-in not working anymore with WordPress 5.8?

I tried to use this plug-in but can’t figure out how to edit all my pages.

The plug-in description says there should be 200 queries per search result, but I only get 58.

Also, how can I see the other posts on my website? I tried searching by publish date, but even then, the plug-in doesn’t show me all posts published in that period.

Searching for the following for example doesn’t show me all results:
2019-04-06..2020-06-06

Then in the plug-in description, it’s instructed to add a parameter on how many posts per page, but also that doesn’t change anything. See here an example of the search I did:

2021-01-01.. posts_per_page=500

Is there anything that I should change in my queries or is the plug-in not working anymore?

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