Wix's automated sitemap generation was not including my pdf files, so I generated my sitemap by having a 3rd party website crawl my site. It picked up the pdf files but I was unable to upload the xml to Wix. XML's are prohibited. I wanted to upload the xml so I could point Google Search Console to it. However, I found that if I changed the extension on the file to .txt, that I was able to upload it, and Google Search Console was able to parse it as an xml, even with the wrong extension. Gotta be tricky with Wix. ha ha
It looks like wix creates separate sitemaps depending on the type of page you have. Are the pdfs registered in the site? ref: https://support.wix.com/en/article/understanding-your-sites-sitemap-file
Wix won't include pdf's in their auto sitemap so you have to make your own. They also will not let you upload a file with an xml extension but you can get past that by changing your file extension to "txt". Then you will have to get the generated name of your text file by finding it in Wix. I forgot to mention that before. Any uploaded file in wix gets a unique file name that they generate for outside reference. That generated name is what you put into Google Search Console to get it to read your "manually" generated sitemap. I generated the sitemap using this site. https://www.xml-sitemaps.com/