Hi Lei,
Welcome to Senaite!
If Senaite has been installed, you should not fear those warnings when running bin/buildout.
So far, the system does not allow to create a sample without creating an analysis request at the same time. Each time you create an analysis request, a sample is created and binded to the same analysis request and the analyses.
But, while you are creating an analysis request, you can reuse an already created sample and all its fields will be automatically filled (date sampled, sample type, environmental conditions, container, etc). See the attached image:
About documentation, you can take advantage of Bika LIMS documentation for now. One milestone in the Seniate roadmap is to create a dedicated website for documentation and to provide an add-on that integrates the context-aware documentation within Senaite.
Regards,