Set up Business Central
Platform, companies and access
Business Central runs in environments created and managed in the Business Central admin center: a production environment plus sandboxes used for testing, training and safe posting experiments. A Microsoft 365 license is assigned in the Microsoft 365 admin center, but access inside the product is controlled by permission sets on the user card, while a profile controls the role center and which UI elements the user sees. User Setup stores the salesperson/purchaser code and the Allow Posting From/To range that restricts each user's posting dates.
Creating companies and moving data
New companies are created from a template through Assisted Setup, by copying an existing company, or manually, and each company needs its own setup. Master data and setup tables are migrated with Configuration Worksheet, Configuration Packages (export/import table data with validation), or Edit in Excel for bulk edits. Configuration packages are the standard answer for repeatable, validated setup data.
Number series
Every card and document that gets an identifier reads it from a number series assigned on the relevant setup page. No. Series Lines hold starting and ending numbers plus the flags Default Nos., Manual Nos. and Date Order; No. Series Relationships chain sequences together, for example one series per fiscal year.
Dimensions
Two dimensions can be global (captured on every entry), others are shortcut dimensions; dimension values are created per dimension, default dimensions are set on master data and accounts, and dimension requirements can block posting when a value is missing.
Traps: questions assume a sandbox behaves differently from production (it does not), or that creating a card before assigning a number series is harmless (it fails). Another trap is confusing license assignment with permission sets, and forgetting that default dimensions on a customer drive the dimension on every document.
Rule of thumb: configure number series and dimensions first, then create master data.