Eclipse would provide its own embedded Maven enviroment out-of-the-box, which is not recommended whenever a certain Maven version must be used or further configuration must be performed (proxy, mirrors and so on): that is, to have full control over which Maven environment would be used by the IDE.
Select Window → Preferences → Maven → Installations
Select Add.. to add a custom/local Maven installation
Supply the necessary information and select Finish:
Installation home: ... your Maven home ...
Directory...
Installation name: Apache Maven x.y.z
☑ select it as default (instead of the default EMBEDDED version) and confirm with OK.