Exactly what I tried to do. Then just fall back to duckduckgo: https://duckduckgo.com/?t=ffab&q=pegasus+mail&iax=images&ia=...
I believe that's how the author earns a living: the software is free (and has online help), but the manual costs money.
Oh, ok, I thought it was bundled with the download.
I went looking into this a bit and TBH I think I'm out of date.
I think he sold printed dead-tree manuals.
Now PDFs are bundled:
The site leaves a lot to be desired, but it loads fast.