URL Re-Write with RegEX

I hope this is the right spot for this question.  We have a Fortigate v5.6.8 and I am hoping that we could use a RegEX to re-write the URl for Zoom invitations to bypass the app install attempts and go directly to the Join in Web Browser page. I wrote a RegEX that checked out on Regex101.com but when we try to use it on our Fortigate nothing happens.

Unfortunately I don't have direct access to our Fortigate as I am a Desktop Admin so my informtation/knowledge on the Fortigate side is limited. Our Sys Admin called Fortigate but they didn't understand what we were trying to accomplish. So in a nutshell we would like to take a URL like: www.zoom.com/j/###### and replace the /j/ part with /wc/join/ so the resulting URL would be www.zoom.com/wc/join/######

When speaking with support we were told to create a URL filter. We selected the Reg. Expression type and tried both Exempt and Allow options but the URL wasn't re-written when we tested it. The RegEX I wrote is this:  (\.(zoom))(\.(us|com))(\/[\j]+)(\/[\w.-]+)$/gm,"$1$3/wc/join$6";

Is this not possible or does the Fortigate have a different syntax?

Thanks!