Hi
JAEM Component worked more than wonderfully for the latest years , from some days Joomlart moved to a new website ( and new servers ) to offer a better service to customers, and some things still need to be fixed , so it is a server configuration problem not a component issue , also this is not a blocking issue anyway since all extensions can still be installed using the Joomla core extension manager
Maybe more comprehension until things will be definitively fixed and everything will come back to work as it was for the last years, could be considered, since everything was done to offer a better service to all.
Best regards