As soon as you open a Design, Flex will download the design locally to your computer. This is when the project gets locked for your colleagues.
This means no other colleague can work on the same project while you are editing anything inside the design. This ensures that your changes are saved correctly without anyone overriding them.
You can see the user and PC name of where the project is open when you double click to open a design.
Should a project be accidentally locked, you can release it inside the Flex platform see article Flex: Unlock a Project and Design
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