Curl: (60) SSL certificate problem

I’m trying to connect my device to my server. I follow steps below:

  3. JWT=$(curl -X POST -u $MENDER_SERVER_USER $MENDER_SERVER_URI/api/management/v1/useradm/auth/login)

After this command, log as below :
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
0 0 0 0 0 0 0 0 --:–:-- 0:00:07 --:–:-- 0
curl: (60) SSL certificate problem: self signed certificate
More details here: curl - SSL CA Certificates

curl failed to verify the legitimacy of the server and therefore could not
establish a secure connection to it. To learn more about this situation and
how to fix it, please visit the web page mentioned above.

I have gone through some similar topic but still cannot find how to solve.
I would like to know why this give that error or I have missed any steps to do/confirm first ?

Thanks in advance.