Trying to use Flyready today for my trip to DFW tomorrow from AMS. Not able to upload docs via mobile and when following the steps on a PC, all I get is a white blank screen where one should upload their proof of vaccination/proof of covid test. Basically can't upload a thing.
Further, on KLM it states checked in, Delta app says unable to complete and im going nuts (first time trip to the US and first ICTL flight since covid)

Additionally, I got an email stating to be 4hours ahead of departure at the airport.. Never heard that one before. Is this really needed or can one just show up 3h ahead? I have Privium Plus on Schiphol side so won't need to queue up for passport control on the dutch border.