To give project leader access JIRA Misc Workflow Extensions plugin

[l]

how to give project leader access to JIRA Misc Workflow Extensions plugin in order to create custom workflow for the project.The user dont have admin acess

[Nic Brough -Adaptavist-]

You don't, the concept is a nonsense. The plugin does not do anything that can be "granted access to", all it does is add functions that can then be called by workflows (as edited by your administrators)