meeting link failed

I scheduled mtg and copied and pasted link and e mailed it  to guests. I opened the mtg from my profile. When others tried to join it said No Meeting Found ( or some such wording), Some then went to their zoom acct and put in mtg number and password and joined in.  From the participants section of the mtg I hit invite and sent it out to one person who quickly emailed it out to others, and that link worked for many to join.  Some minutes later a blurb came in the top corner of my zoom screen and  said "Mtg link now active." (or some such wording).   Zoom, what happened here? and how can I avoid this happening again? A very bad start to the meeting and some never got on.