Hello,
You can use the below KB article to export a route from master routing instance to a virtual router :-
https://kb.juniper.net/InfoCenter/index?page=content&id=KB19860&actp=search
Though the above Kb article is for EX-Series devices but it hold true for the SRX devices as well and the same configruation is required on SRX as well.
Hope this Helps
Thanks,
Pulkit Bhandari
Please mark my response as Solution Accepted if it Helps, Kudos are Appreciated too.