Ok. I managed to install the lastest version after a bit of timeout issue. Not sure if it is because my test machine is a bit slow but during the database upgrade I had a 504 Gateway timeout.
After reload the page I still wanted to apply the last patch (the one about the foreign key)
Eventually it worked so I could test sending email…and it still fails…I get the following message
Both pdf_string and pdf_file_name must be set or left empty