First of all, every installed app should be in /tomcatpath/tomcat/webapps/, not in the tomcat/ homedir.
My guess would be to remove the installed cmdbuild instance and install it again at tomcat/webapps. Make sure to drop database from previous attempt.
Before starting new installation process, check whether tomcat manages to start.
$ Systemctl start tomcat.service
Is your fastest way to go.
If tomcat starts throwing weird errors, my choice after an hour or so was to reinstall tomcat. I have to say tho, I managed to mess a few things in it before finding my way around.
Anyways, when installation is done properly, You will find your cmdbuild at http://ip_address:8080/cmdbuild
protip1: get to know http://ip_address:8080/manager - it helps debugging, if tomcat sees an app etc.
protip2: however you name your app directory in webapps/ will be the name of the app. So if you go for webapps/mynewcmdb/(actual cmdbuild files)
the link will change to http://ip_address:8080/mynewcmdb