You can always ask the EC help desk "Research Enquiry Service". Bear in mind the following:
"Please submit your questions concerning calls for proposals at least two weeks before the respective call deadlines - we can not provide an answer in time otherwise.
* The service does not provide help on: forgotten passwords
(experts, proposals, etc.), technical aspects of proposal submission, or
IT problems (use relevant help-desks refer on EPS pages)."
And also always check the FAQs of the EC!
The MSCA explained by your National Contact Points