Thank you for your post.
How was this PDF created? If you use the PDFs that come with FileMaker Pro Advanced 14 (FMP Acknowledgements.pdf, FMP Read Me (English).pdf, FMPA License (English).pdf), you can copy and paste without any issue. With your PDF, you can only paste the text (Edit menu -> Paste Text Only).
Thanks for the hint.
Not sure how PDF was created but I found now two suitable solutions:
Use Foxxit Reader
Use Adobe Acrobat reader with the function "copy with format" (ony CTRL-C does not work)
Solved! Thanks for the help!