Microsoft Access can technically allow 255 connections for each database. However, this is a theoretical limit and cannot be attained in an organization. In reality, the number of connections or users that an Access database can support is dictated by how well the application was designed and implemented.
For example, a professionally designed and well-tuned Access application can support up to 20 concurrent users who are updating data with good performance. Databases that are used largely for running read-only reports can scale up to about 100 users.
Unfortunately, few Access databases are well-designed and implemented with best practices. This is because most Access databases are created by beginners or power users who do not have the experience or knowledge to create professional applications. They are built over time, and new features and data models are added as needed. The result is that many solutions don’t reliably support more than a few users.