Great to hear that you have successfully downloaded the browse-flows app.
sFlow-RT does not keep a history, you will need to use an external database (Prometheus, InfuxDB, Logstash etc). Here are a couple of examples:
PS Please don't drop the list when replying.
i use docker run --rm -v $PWD:/sflow-rt/app --user=root --entrypoint /sflow-rt/get-app.sh sflow/sflow-rt sflow-rt
How to save 30 days of flow records?