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Please check the link below to make sure that the POS version you are having is compatible with your current Magento version.
Prerequisite
Magestore POS Line 4 (POS Pro 4, POS Pro Commerce 4, POS Enterprise 4, POS Enterprise Commerce 4) requires MSI to be installed and enabled before installing the POS. You can follow the guide Install Inventory Management from Magento to install and enable MSI.
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