Answer to many questions about Alidropship can be found in Alidropship Knowledge Base. See this link: https://help.alidropship.com/en/articles/2237021-available-payment-gateways. All payment gateways supported by Alidropship is there. Each payment gateway has the list of countries it is available. Paypal is one, and it has the list of countries that it is not available below. Sri Lanka is not in the list, so it should be available in your country, if the list is accurate. Have you tried Paypal? You need to know how to find answer to this kind of question, not simply post it here.