I had tested this on a Raspberry Pi 3 which was working fine. I'm not sure if there's any resource limitation on the Pi 2 that would cause potential issues. I however had some performance issues when using the H2 version, therefore I stuck to the Neo4J version.
As there were some changes introduced in ThingWorx 7.4 I would also stick to 7.2 or 7.3.
If the Tomcat folder exists in the webapps, that means that initial deployment has been successful.
I'd recommend checking the Tomcat logs and the ThingWorx ApplicationLog / ConfigurationLog for any potential issues.
