I would suggest to use CentOS 8 because 7 does not have the a right PostgreSQL version for Tryton 5.6 (and further). Also CentOS 8 has default Python 3 installed.
You can use Docker or install Tryton into a Python Virtual Environment and use pip to install Tryton. I would not suggest to use Installing tryton(d) 5.2* on ubuntu 18.04.3 with postgres 11 for newbys by newby because it will mess up your system as you are using pip globally on the system.