
Review these blogs before creating a database on an ODA:
The Oracle Database Appliance [ODA] is a family of engineered systems which are designed to be database servers. These Linux x8664 based systems are simple, affordable and optimized for database workloads. These engineered systems are a combination of hardware and software with certified configurations. By using certified configurations, customers can focus on using optimized systems rather than trying to figure out how to build and optimize a combination of CPUs, memory, storage devices, networking, operating systems, file systems and databases.

TimesTen can be used in several different configurations as either a cache or as a system of record. When TimesTen is used as a cache to an Oracle Database, the Oracle Database can be any of Exadata, ODA, RAC or single instance.
A. TimesTen Classic can be used as a read only or read/write cache to an Oracle Database
Either the ODA X8-2S or X8-2M can be used depending on the TimesTen database cache size.
B. TimesTen Classic can be used as a read only or read/write cache to an Oracle Database with high availability via replication
The ODA X8-2-HA can be used as an high availability configuration for TimesTen replication.
C. TimesTen Classic can be used as a system of record with high availability via TimesTen replication
The ODA X8-2-HA can be used as an high availability configuration for replication.
D. TimesTen Scaleout can be used as a read only cache to an Oracle Database when used as a target for Oracle GoldenGate
Either the ODA X8-2S or X8-2M can be used for each TimesTen Scaleout instance depending on the TimesTen database cache size.
E. TimesTen Scaleout can be used as a system of record
Either the ODA X8-2S or X8-2M can be used for each TimesTen Scaleout instance depending on the TimesTen database size.
The way to install TimesTen on an ODA is the same for all ODA models and is the same whether TimesTen is used as a cache or as a system of record.
The Oracle Database Appliance must have Oracle Clusterware and ACFS 18c or 19c installed and the ACFS volumes mounted.
SSH onto the ODA machine
Determine an OS user which has the same primary group as the Oracle Clusterware installation owner. eg if Oracle Clusterware is installed as user grid with primary group oinstall, then an OS user like oracle which has oinstall as its primary group should be used.
As user oracle, create a directory for the TimesTen installation, eg /opt/timesten. This directory should not be part of an ACFS volume mount. ie mkdir /opt/timesten
Download the TimesTen Linux x8664 software from oracle.com, eg timesten181320.server.linux8664.zip
As user oracle, copy the TimesTen zip file to the /opt/timesten directory
Unzip the TimesTen zip file in the /opt/timesten directory. This will result in a new directory eg /opt/timesten/tt18.1.3.2.0
The unzipped directory structure, eg /opt/timesten/tt18.1.3.2.0 is known as the TimesTen Installation. An installation is a read only copy of the TimesTen software.
If you are creating an Active Standby Pair on ODA then repeat the installation steps on the other ODA node using the same OS user and the same directory structure.
A TimesTen instance are the read/write configuration files.
To create a TimesTen instance, do the following:
If you need to modify these instance values, you can use the ttInstanceModify utility to change them.
This should result in the creation of a TimesTen Instance directory structure, eg /opt/timesten/tt181
The TimesTen main daemon should also be running. eg
Starting the daemon ...
TimesTen Daemon (PID: 92753, port: 6624) startup OK
You can verify that the TimesTen main daemon is running via 'ps -ef | grep tend'

If you plan to create an Active Standby Pair on ODA then repeat the instance creation steps on the other ODA node using the same OS user and the same directory structure.
See the following blogs for more configuration options:
Disclaimer: These are my personal thoughts and do not represent Oracle's official viewpoint in any way, shape, or form.