Most off-the-shelf CRM and ERP apps seldom do exactly what the user wants. This is because beyond the ubiquitous basics, every business/organisation/company has its own unique processes, nomenclature and methodologies. Ready-made apps are not designed with these peculiarities in mind.
Consequently, users are forced to put up with various inadequacies and deficiencies. To remedy this, I design custom-built ERP solutions in Microsoft Access. And depending on the nature of the project and needs of the client, the actual data may be stored in Microsoft SQL Server. The location of the data could either be a local/on-premises installation or a cloud installation such as Microsoft Azure or Amazon AWS.
User Interface and User Experience Design (UI/UX) is something many developers fail to do properly.
Microsoft SQL Server