From the US, I applied for the Belgium digital Covid certificate via the coronavirus.Brussels website where there was information for foreign visitors (Belgian CST for foreigners section.) I filled out the information, uploaded my digital vaccine information and passport information. It asked for information about the European vaccine name, so I had to select both Spikevax and Moderna. You may want to look that up for whatever your vax is. It took only a couple of days for them to validate. everything, and sent me back an email. I also gave them my phone number which is important. When I received the email it told me to download CovidSafeBE, and gave me a code to download the certificate. I did not need to download any other application. However I did need to provide the last four digits of my phone number, although I only received a code via email. So remember to enter a phone number when you apply. I entered the code and digits, and immediately had my information linked. I don’t know about the problems people of had been asked to download a different app, and I didn’t download any test results. But I was able to do this directly from United States after getting the digital certificate from the website.