Dear iamlimo,
Thank you for reaching out.
As a System Integrator, your role is to build accounting solutions that fully comply with the government’s e-Invoicing standards or support taxpayers in standardizing their existing accounting systems.
Accordingly, you are expected to either work directly with a taxpayer who has both sandbox and production access, or onboard yourself as a taxpayer on the e-Invoicing platform. These requirements have been explained from different perspectives within this community.
We kindly advise that you search existing discussions before creating a new question, as many common topics have already been addressed.