The Zephyr for JIRA plugin will get installed in few minutes. It will not take much time. In order to better assist you in this regards, I would suggest you to open a support case by accessing the below link with the following details-
https://support.getzephyr.com/hc/en-us ( After clicking on the link please select 'Submit a Case' icon in the support page, fill the details and submit it)
Thanks & Regards,
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