I use ring central, my customer uses zoom.....

Yes, by using the meeting ID.  I don't think using the invite link would work.  He would just open Zoom and put in the 10-digit meeting ID.

I would also like to know the answer to this.  Please post the result.

Ring Central uses Zoom under the surface is it's meeting client - so as  Bob says it should be possible.

I tested it.  Granted, it was on a machine that has RC Meetings and the Zoom client installed, but I started a RingCentral Meeting and then opened the Zoom client and clicked Join Meeting then put in the 10-digit meeting ID and it worked.  I can test on a PC that doesn't have RC Meetings installed to be sure.

Note that this is the answer today.  There's certainly no guarantee that RC will continue to use Zoom as the foundation, and there's also no guarantee that Zoom will always recognize RCM meeting IDs.