multi-user system sought (non-cloud)

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I am a long term GC user but have grown-out of it a little with our
companies accounting requirements.

main issue ... I need a multi-user simultaneous access system for our company.
Furthermore it should be a local thing. I can not access any online or
cloud platforms.

Can someone here recommend any (Open Source) accounting system? A full
blown ERP system (like Odoo or ERPNext) is too complex at this point
in time yet though, so it should be a standalone accounting system.

thanks & best
Gunnar