Hello @JerryMeister ,
Actually I just find that the Join Link seems to be a little different for every registed users:
https://teams.microsoft.com/l/meetup-join/19%3ameeting_NmE0MTgwM2QtYjlhYS00ZDZkLWExNGQtZTYyN2RkNDU5OTQy%40thread.v2/0?context=%7b%22Tid%22%3a%226e6e325b-3d18-4c22-ad88-a9b95bd47bd0%22%2c%22Oid%22%3a%2268929419-7b74-423c-b68a-fd9498f9fe4c%22%2c%22prid%22%3a%22WzJubhg9IkytiKm5W9R70A%2cAtia2zZmyEesFaJlJ_2Vsw%2cImnaJlyNoEWuIwnoai2TwQ%2cUArbdf0_CkKeKdYU69CZNA%2cLY8PKuwLpEGfeMgo0eH-uA%2chBg5p97Yt0-XXX%**2ccgrZDF1v92le7p0ZozTnVw**%XXX
I replaced some part of the URL to XXX, but they are also the same. The last one is the original meeting invite URL.
All these three links could be used for every user. I think you could copy one of them or just use the meeting link.
Sorry I don't know how the Campaign Monitor works or how you want to send the join link to these users, if you could share more information about the process, I could do a further research about it. And also kindly suggest that you may contact the third-party software support for helps for the software self questions.
Best regards,
Lou