As we work with a third party as payment provider, this (KYC) process is fully managed by them and so, we have no control over the approval or rejection of your ID document / passport.
There could be several reasons for a document rejection. Please find them here.
For more information on what documents are accepted per country, please find the overview here.
It's often better to upload a scanned version of your document rather than a photo and the information on the document must match the information as reported in your "profile".