No worries. 
I was surprised to find the text was not searchable upon downloading the REGO-FIX documents. I had to OCR the file to make it completely readable and editable.
Mac user here, with PDF format being native to MacOs. I use the excellent PDF Expert application as well.
Strange
Hey QCDvacuum,
here, both https://de.rego-fix.com/system/files/docs/2024-08/ER_Flyer_ENG.pdf and https://de.rego-fix.com/system/files/docs/2020-08/REGO-FIX_Main_Catalogue.pdf (which redirects to https://www.yumpu.com/user/rego.fix and finally leads to https://www.yumpu.com/en/document/download/63820363/f0055-ce19f-046ae-ef85f-48731-04eeb-66a3e-c4a12) do successfully download as searchable PDF files, whether fetched with Vivaldi, Chromium or wget. I can do full text search through these pdfs in either Xpdf, Atril or Evince. All three are Free and Open Source Software. So I can’t replicate the issue you encountered 
Many thanks for the links @Aiph5u ~ I was able to download normal .pdf files when I first set up my spindle more than one year ago. It is a mystery to me because .pdf files are easily configured at the time they are saved. I no longer have Acrobat so I cannot dissect the files.