All three accounts has free licence inactive. For account firstname.lastname@example.org we used free licence at the begining and next we moved it to Pro licence. The remaining two accounts was always Pro.
We will expunge the 'Free' licenses so you can try to launch from the website again to confirm success. Please let me know.
All accounts are working well now, meetings can be started from web browser.
Thank you for help.
Great! Thanks for confirming the fix!