The Pro Plugin destroys the Site (Support doesn’t help)

The free plugin worked so well that I bought the Pro plugin.
Unfortunately, after activating it, the site broke down. Error 500. After trying to install the Pro plugin together with the free plugin, then without the free plugin, and even on a test site where the Pro plugin was installed for the first time, I had to restore a backup every single time and wasted about 3 hours of my life.
The support responded quickly, but wanted admin access to my site and when I didn’t grant it, they refused a refund and weren’t very friendly either.
I won’t open a PayPal dispute for that small amount of money, but I definitely cannot recommend buying this plugin. The only question was whether to give 1 or 2 stars, because the free plugin does work.