SII was for splunklight, it was not intended to be multi tenant, initially. SAI is an app for enterprise, but the setup UI still assume that you have single instance (SH/IDX all in one).
So when you are in an enterprise splunk deployment, read the docs :
https://docs.splunk.com/Documentation/InfraApp/2.0.0/Install/DistributedDeployment
You do not really want to send data to the SH , its a bottleneck, and HEC may not scale.
Instead move the ingest on the indexers.
you need to create the HEC tokens and inputs on the indexers, install the TA (with sourcetypes and indexes)
setup a DNS loadbalancer to have a single address for all your indexers
then customize the install script for the client to use the good token and the indexers addresses
... View more