Share Custom Connector with multiple users

send them the .mez file and show them where they need to store it.

Share with them the mez file, and let them place it in: \Documents\Power BI Desktop\Custom Connectors folder. If the Power BI Desktop or Custom Connectors folders don't exist then you can create them manually. Don't forget to let them enable the (Not Recommended) Allow any extension to load without validation or warning Under File > Options and settings > Options > Security > Data Extensions

for more information feel free to check : Connector extensibility in Power BI - Power BI | Microsoft Learn