Error in Step 3: Sign API Requests

Using https://gethttpsforfree.com/ to get an ssl certficate, I got this Error: You need to run the above commands and paste the output in the text boxes below each command. This happened in step 3. All went well until this step. The stdn I received after pasting code (PRIV_KEY=./account.key; echo -n "eyJ1cmwiOiJodH....) supplied by your website looked good ((stdin)= 99643ce8ae61.....) but I received the above mentioned error. Server OS is Opensuse Leap 15.1. Please advise me on how to deal with this. Many thanks in advance.

Regards,
Rich