API ORDERS not working

try the demo server.if it is working then real server will work for sure

do a frsh installation from https://www.ads-software.com/plugins/search/smm-api/

the errors are fixed

Also the purchase page for the premium version does not work

For pro or commercial product support please contact the developer directly on their site. This includes any pre-sales topics as well.

As the developer is aware, commercial products are not supported in these forums. I am sure they will have no problem supporting you there.