JD Coax is a paid template, so you won't get auto updates then in that case you will have download the JD Coax Template zip file from the Download manager(www.joomdev.com/my-downloads/jd-coax) and install it over your already created setup.
But before doing this I would suggest you to take a backup of the older version just in case you loose the changes, because we don't know what changes you made so in case anything happens we won't be responsible.
After updating do let us know if there still is any issue.
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