BonitaBPMCommunity 6.4.2, Ubuntu 64bit: Tomcat not starting

Hello, I have downloaded BonitaBPMCommunity-6.4.2-x86_64.run; made BonitaBPMCommunity-6.4.2-x86_64.run executable; run in a terminal by ./BonitaBPMCommunity-6.4.2-x86_64.run. Installation (English/English) says: everything fine, want to start Bonita? I said yes. I had choosen all defaults (e.g. installation folder). The Bonita Studio (?) starts, I can import a downloaded BPMN (os_procurement-3.0.bos) but after a while there is an error message: