Can't export files as xliff even the original file is xliff format

Hello,

I have 2 different projects from different clients but the result is the same and I'm confused now. Client A sent me Xliff file, done translation, can't export the file as Xliff. The original file was pptx (and the client A converted to Xliff), so I can only export as pptx. Client B sent me word file, done translation, can't expoert the file as Xliff. Only Word file. 

I'm using Trados Studio 2022 and Online Editor but both export the same file format. How can I extract files as Xliff?

emoji