My client hasn't updated to Trados 2021, but I did. Now I can't download their files from World Server because Trados 2021 doesn't recognize Trados 2019 files from World Server. I tried to go back to Trados 2019...

I tried to go back to Trados 2019, but my license for Trados 2019 disappeared. I opened a case, which now is closed, but I was instructed to use Trados 2019 trial version, and then I was told Trados 2019 would automatically pick up my license for 2021 into Trados 2019. Trial version has expired, and the program didn't pick up the 2021 license as the support said. I tried to copy and paste the activation code for 2021 into 2019, but it was not accepted. What should I do now?