Where can i get free covid test /certificate for travelling? I have qatar id & not health card.

can i just go to any walkin health centre & they will give me covid result? is it by email or sms (eg how can i get printed copy for qatar airways?)

im travelling in jan. Do i need to show them printed ticket to get covid test for travellers? Please help, iVe tried calling many hotlines & they did not give me any info